OS X Glossary Contents Introduction to OS X Glossary 3 Organization of This Document 3 Glossary 4 Document Revision History 143 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 2 Introduction to OS X Glossary The OS X Glossary defines terms used in the OS X Reference Library. Some definitions vary by technology, in which case more than one definition is provided. Some of these terms are specific to OS X or other Apple products and technologies, while others are commonly used in computer-related endeavors. Additional knowledge of computing and data processing may be needed to fully understand some of the terms. You can refer to this document to better understand terminology used in OS X and other Apple products, technologies, and documentation. Organization of This Document This document contains one chapter, Glossary (page 4), that defines OS X terms in alphabetical order. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 3 Glossary 5.1 Surround Sound A surround sound speaker configuration consisting of five speakers arranged in specific positions along the circumference of a circle and a subwoofer (the “.1”). The speaker channels are typically designated as follows: left, center, right, left surround. right surround, and LFE (low frequency effect). application object to be complete, its outermost container must be the application itself. Compare relative object specifier. absolute position A specific position, given in coordinates, for the origin of each character or glyph in a line of text. Compare absolute object specifier. abstraction (1) The process of separating the interface to some functionality from the underlying implementation in such a way that the implementation can be changed without changing the way that piece of code is used. (2) The API (interface) for some piece of functionality that has been separated in this way. 8.24 Sometimes written as Q8.24 or fx8.24 . A fixed-point sample size used as the canonical audio sample type for processing linear PCM audio in iOS, in lieu of 32-bit floating-point samples. In an 8.24 audio sample there are eight bits to the left of the radix point, forming the integer (or “magnitude") portion of the value, and 24 bits to the right, forming the fractional portion. abstract type In information property lists, a type that defines general characteristics of a family of documents. Each abstract type has corresponding concrete types. See also concrete type. AAC Advanced Audio Coding. A compressed, lossy, perceptual coding scheme, originally a component of the MPEG-2 standard as MPEG-2 AAC. Defined in 1997 as part of ISO/IEC 13818-7. Enhanced for the MPEG-4 standard as MPEG-4 AAC. MPEG-2 AAC provides better perceived audio quality at the same bit rate compared to MPEG-1, layer 3 ( MP3), according to results published in ISO/IEC JTC1/SC29/WG11, N2006 (February 1998). MPEG-4 AAC extends MPEG-2 AAC with additional coding tools. See also lossy compression. AC-3 A compressed, lossy, perceptual audio coding format developed by Dolby Laboratories, Inc. Sometimes called Dolby Digital or Dolby Surround AC-3 . See also lossy compression, perceptual coding. Accelerate framework An OS X framework that serves as a container for several other frameworks related to optimization and high performance. access control entry See ACE. About window A modeless window that displays an application’s version and copyright information. access control list See ACL. absolute object specifier An object specifier that has enough information to identify an object or objects uniquely. For an object specifier to an accessibility The successful access to information and information technologies by people with disabilities. OS X provides support for users with disabilities in the form of VoiceOver (Apple’s 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 4 Glossary full-featured screen reading technology), speech recognition and text-to-speech features, and mouse and keyboard alternatives. OS X includes the accessibility programming interface, which defines how an assistive technology, such as a refreshable braille display or head-tracking mouse, can communicate with and control an application. action (1) In OS X, a connection that involves the sending of a message from one object to another when a certain user action occurs. For example, when a user presses a button, the button object calls the action method of its target object to notify that object that the action occurred. (2) In Automator, a building block used to build workflows. access layer The classes in the package com.webobjects.eoaccess , which include the model-level classes EOEntity, EOAttribute, and EORelationship. You usually do not work with classes in this layer directly, but rather indirectly through the EOModel class. action button The button that confirms the message text in a dialog. The action button is in the lower-right corner of a dialog. It is often, but not always, the default button. action line In Xcode, the code line indicated by the pointer at the time you choose a debugging command from the shortcut menu. access object An opaque data structure containing one or more access control lists (ACLs). Each keychain item has one access object. action object In Xcode, the object on which you want to perform an action. access permissions See permissions. activate To bring a running application to the front of the screen, allowing the user to interact with it. Compare launch. access rights See permissions. accumulating attribute group A set of attribute choices in which the user can select multiple items, such as Bold and Italic. Compare mutually exclusive attribute group. active In iOS, used to describe an audio session state in which playback or recording can proceed. Compare inactive. active build configuration The build configuration Xcode uses to build the active target and any targets it depends upon. See also build configuration. ACE Access control entry. A component of an ACL that associates a user or group with a set of permissions and specifies whether each permission is allowed or denied. See also Unicode Utilities. active driver A device driver that implements advanced power management tasks, such as determining device idleness and performing pre-shutdown tasks. Compare passive driver. ACL A structure containing information describing what must happen (display a confirmation dialog, ask for a password, and so forth) in order to permit a specific operation to occur. An ACL may also contain a list of applications that are always trusted to perform that operation. Each keychain item has one or more associated ACLs, and each ACL applies to a single operation that can be done with that item, such as encrypting or decrypting it. See also access object. active end The point at which the user releases the mouse button when selecting a range of text or other items. Compare anchor point. active executable The executable environment that Xcode uses when you run or debug a product. See also executable environment. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 5 Glossary active extension A filename extension claimed by at least one application registered with Launch Services. Compare valid extension. quantization error and other distortion characteristics, and noise floor. Professional audio work usually employs ADCs with a linear response. Compare DAC. See also quantization, sample. active SDK The SDK used to build a product and the runtime environment on which the product is to run. See also SDK family. addition model A model for extending a continuous selection using Shift-click, in which new text is added to a selection. Compare fixed-point model. active target The target that Xcode uses when you build the project. See also string atom. Address Book A technology for managing names, addresses, phone numbers, and other contact-related information. OS X provides the Address Book application for users to manage contact data. It also provides the Address Book framework so that applications can programmatically manage the data. active window A window that applies to the user’s current task. Active windows are distinguished from inactive windows by the look of the title bar and the window controls. The active window is typically the frontmost non-floating window, but multiple windows can be active simultaneously. See also key window, main window. address space The virtual address ranges available to a given task (the task may be the kernel). In OS X, processes do not share the same address space. The address spaces of multiple processes can, however, point to the same physical address ranges. This is referred to as shared memory. adaptor layer In WebObjects, a sublayer of the access layer that provides classes that communicate directly with data sources. adaptor (1) For databases, a mechanism that connects your application to a particular database server. For each type of server you use, you need a separate adaptor. WebObjects provides an adaptor for databases conforming to JDBC. (2) In WebObjects, a process (or a part of one) that connects WebObjects applications to an HTTP server. admin group A group with special administrative privileges. For example, only members of the admin group can open locked system preferences or install software. See also wheel group. administrator A user in the admin group. The user who installs OS X is automatically assigned to the admin group. An administrator has fewer privileges than root, but more privileges than a normal user. An administrator cannot create, delete, or move files in the system domain. ADC (1) Apple Developer Connection. The primary source for technical and business resources and information for anyone developing for Apple’s software and hardware platforms anywhere in the world. It includes programs, products, and services and a website filled with up-to-date technical documentation for existing and emerging Apple technologies. (2) Analog-to-digital converter. Circuitry that converts analog signals to corresponding digital code using sampling and quantization. ADCs are characterized by sample rate, amplitude resolution in terms of bit depth, ADPCM Adaptive delta pulse code modulation. A variant of pulse-code modulation, and an extension of DPCM, that varies quantization step size to minimize bit rate for a given dynamic range. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 6 Glossary advance delta The distance between the end of one glyph’s advance and the next glyph’s real position. 'aete' resource A resource that serves as the traditional mechanism for providing scriptability information in a Carbon application. An 'aete' resource can also be included in a Cocoa application to control how scriptability information is displayed in a dictionary viewer, by applications such as Script Editor and Xcode. Starting in OS X version 10.4, it is not needed for this purpose, for applications that supply their scriptability information in the sdef format. advance height The distance from the top of a glyph to the bottom of the glyph, including the top-side bearing and bottom-side bearing. advance width The full horizontal width of a glyph as measured from its origin to the origin of the next glyph on the line, including the side bearings on both sides. AFP Apple Filing Protocol. A file-sharing protocol, used by AppleShare servers and clients. AES Audio Engineering Society. An international society of audio professionals that has established many important standards related to digital audio. aggregate device A set of two or more audio devices interconnected to allow the set to be addressed by software applications as a single device. See also device. AES-3 A digital audio transport standard defined by the Audio Engineering Society, originally published in 1992. Also called the AES/EBU interface . Equivalent to IEC 60958 Part 4. The AES-3 standard includes parts for various physical connections including balanced twisted-pair wire, unbalanced coaxial cable, and optical fiber. The technical inspiration for AES-3 was the S/PDIF standard. aggregate target In Xcode, a combination of targets, not necessarily dependent on each other, that does not produce a product or contain build rules or information property list entries. An aggregate target exists so that you can make it dependent on other targets. The build system builds the targets that the aggregate target depends on sequentially or in parallel. AES encryption Advanced Encryption Standard encryption. A Federal Information Processing Standard (FIPS), described in FIPS publication 197. AES has been adopted by the US government for the protection of sensitive, nonclassified information. The algorithm was developed by Dr. Joan Daemen and Dr. Vincent Rijmen and was named the Rijndael algorithm. It is a symmetric-key algorithm that can use key sizes of 128, 192, or 256 bits. Apple has adopted the 128-bit version of AES for FileVault. There are approximately 3.4 x 10**38 possible 128-bit keys. AGL framework Apple Graphics Library framework. The Apple framework for using OpenGL graphics in Mac apps written in the Carbon environment. AIAT Apple Information Access Toolkit. In Classic Mac OS, an object-oriented information access engine that contained a collection of tools for indexing, searching, and analyzing large volumes of documents. Search Kit is the OS X implementation of the AIAT. AIAT was formerly known by its code name V-Twin. AES/EBU interface An alternate name for AES-3. See also EBU. AIFC Audio Interchange File Format Extension for Compression. An extension of AIFF that supports storage of either compressed or uncompressed audio 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 7 Glossary data. May also be abbreviated as AIFF-C . With the availability of newer audio compression schemes such as MP3 and AAC, AIFC is rarely used. It is still supported in OS X. must be low-pass filtered to remove energy at or above the Nyquist frequency before sampling. Anti-aliasing operations can be performed to prevent or mitigate the results of aliasing. See anti-aliasing. AIFF Audio Interchange File Format. A digital audio file format developed by Apple, Inc., based on the Interchange File Format (IFF) developed by Electronic Arts, Inc. The audio data in an AIFF file is uncompressed, big-endian PCM and is stored in chunks. See also synchronous, linear PCM. alignment The horizontal placement of lines of text with respect to the left and right edges of the text area. Alignment can be left, right, centered, or justified (flush on both left and right edges). alpha The graphics state parameter that Quartz uses to determine how to composite newly painted objects to the existing page. At full intensity (alpha =1.0 ), newly painted objects are opaque. At zero intensity, newly painted objects are invisible (alpha =0.0 ). alert A dialog that appears when the system or an application needs to communicate information to the user. Alerts provide messages about error conditions and warn users about potentially hazardous situations or actions. alpha channel A channel dedicated to representing how opaque a given pixel is. Unlike the red, green, and blue channels, which specify the intensity of their respective colors, the alpha channel specifies the opacity of the entire pixel. For example, if a pixel was defined using float values ranging from 0.0 to 1.0, an alpha channel intensity of 1.0 would indicate 100% opacity, and an intensity of 0.0 would indicate 0% opacity, or transparent. algorithm A sequence of actions to accomplish some task. In cryptography, refers to a sequence of actions, usually mathematical calculations, performed on data to encrypt or decrypt it. alias A lightweight reference to files and folders in Mac OS Standard (HFS) and Mac OS Extended (HFS+) file systems. An alias allows multiple references to files and folders without requiring multiple copies of these items. Aliases are not as fragile as symbolic links because they identify the volume and location on disk of a referenced file or folder; the file or folder can be moved around without breaking the alias. See also symbolic link. alternate track A movie track that contains alternate data for another track. QuickTime chooses one track to be used when the movie is played. The choice may be based on such considerations as image quality or localization. See also track. aliased Said of graphics whose edges appear jagged; can be remedied by performing anti-aliasing operations. Anatomical Transfer Function See HRTF. anchor For documentation sets, a location within an HTML file. When loading the documentation node’s landing page, Xcode scrolls to the location of this anchor. See also documentation node. aliasing The introduction of distortions or artifacts into digital information during processing operations. In graphics, aliasing can cause edges to appear jagged. In audio, aliasing results in artifacts below the Nyquist frequency, sometimes called aliasing distortion . To avoid aliasing, audio signals anchor certificate A digital certificate trusted to be valid, which can then be used to verify other certificates. Anchor certificates can include root 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 8 Glossary certificates, cross certified certificates (that is, certificates signed with more than one certificate chain), and locally defined sources of trust. API Application programming interface. A set of classes, protocols, methods, functions, and data structures that define the interface (calling convention) by which an application program accesses a service. This service may be provided by the operating system, by libraries, or by other parts of the application. anchor point The point at which the user presses the mouse button to begin selecting a range of text or other items by dragging through them. The anchor point is at one corner of the range of objects. Compare active end. API reference search A search type that looks through the available reference for a symbol name. angle In DVD-Video, a specific view of a scene, usually recorded from a certain camera angle. Different angles can be chosen while viewing the scene. API-based adaptor An HTTP adaptor based on a programming interface specific to a particular web server. It allows CGI-like tasks to run as part of the main server process, avoiding the creation and termination of a process for each request. angled caret A caret whose angle in relation to the baseline of the display text is equivalent to the slant of the glyphs making up the text. AppKit A Cocoa framework that implements an application’s user interface. The AppKit provides a basic program structure for applications that draw on the screen and respond to events. animation A visual technique that provides the illusion of motion by displaying a collection of images in rapid sequence. AppKit framework Defines classes to support a graphical, event-driven user interface for applications. See also Cocoa framework. animation proxy An object that stands in for another object and provides animation capabilities without significantly impacting the original object’s API. Apple Core Audio Format See CAF. anonymous memory Virtual memory backed by the default pager to swap files, rather than by a persistent object. Anonymous memory is zero-initialized and exists only for the life of the task. See also default pager, task. Apple Developer Connection See user focus. Apple event A high-level operating-system event that conforms to the Apple Event Interprocess Messaging Protocol (AEIMP). An Apple event typically consists of a message from an application to itself or to another application. anti-aliasing A technique that smoothes the roughness in images or sound caused by aliasing. During frequency sampling, aliasing generates a false (alias) frequency along with the correct one. With images this produces a stair-step effect. Anti-aliasing corrects this by adjusting pixel positions or setting pixel intensities so that there is a more gradual transition between pixels. Apple Event Manager The OS X API for creating and sending Apple events, and for receiving, extracting information from, and responding to them. Apple event translator A part of Cocoa scripting that uses scriptability information supplied by an application to evaluate an Apple event received by 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 9 Glossary the application. In many cases, an Apple event is translated into a script command object that performs the action specified by the event. AppleScript component The scripting component in OS X that implements the AppleScript scripting language. A scripting component provides services for compiling and executing scripts (and relies on the relationship key). Apple Help The component that enables applications to display HTML files in Help Viewer, a simple browser. AppleScript Kit A framework that supplies advanced Cocoa scripting support and other features required by AppleScript Studio. Apple Information Access Toolkit (AIAT) In Classic Mac OS, an object-oriented information access engine that contained a collection of tools for indexing, searching, and analyzing large volumes of documents. Search Kit is the OS X implementation of the AIAT. AIAT was formerly known by its code name V-Twin. AppleScript object A distinct object in an application or its documents that can be specified in a script. AppleScript object class A category for AppleScript objects that share characteristics, such as properties and elements. Apple Lossless A compressed, lossless digital audio encoding format defined by Apple, Inc. See also lossless compression. AppleScript object model A hierarchical structure that, for a given application, specifies the classes of objects a scripter can work with in scripts, the accessible properties of those objects, and the inheritance and containment relationships for those objects. Apple menu A menu that provides items that are available to users at all times, regardless of which application is active. It is the leftmost menu in the menu bar. Apple Public Source License Apple’s Open Source license, available at http://www.apple.com/publicsource. Darwin is distributed under this license. See also open source. AppleScript script file A file with the extension .applescript that contains statements in the AppleScript scripting language. AppleScript Studio A development environment and application framework that combines features from AppleScript, Xcode, Interface Builder, and the Cocoa application framework to provide a sophisticated environment for creating AppleScript Studio applications. apple_ref An informal name for a token identifier that uses the prefix //apple_ref. See also token identifier. AppleScript A scripting language that makes possible direct control of scriptable applications and scriptable parts of OS X. AppleScript Studio application A Mac app that combines AppleScript scripts and Cocoa user-interface objects. AppleScript command A script command provided by AppleScript. AppleScript commands do not have to be included in tell statements. AppleScript text editor An Xcode pane for editing and compiling AppleScript script files (files with the extension .applescript ). The editor relies on the osacompile shell tool to compile scripts. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 10 Glossary AppleTalk A suite of network protocols that is standard on Macintosh computers and can be integrated with other network systems, such as the Internet. application-modal A window state where the user cannot do anything else within the application until the window is dismissed. Compare document-modal, system modal. application A specific style of program that displays a graphical interface to the user. application-modal dialog A dialog that prevents the user from performing any operations within the owner application other than those in the dialog. See also document-modal dialog, sheet, system modal. application bundle A bundle containing the executable code of an application and its associated resources. application object (1) An object stored in an application or its documents and managed by the application. (2) An object (of the WOApplication class) that represents a single instance of a WebObjects application. The application object’s main role is to coordinate the handling of HTTP requests, but it can also maintain application-wide state information. application command A command that is defined by a scriptable application to provide access to a scriptable feature. An application command must either be included in a tell statement or include the name of the application in its direct parameter. application file A file containing the executable code of an application. application package A file package containing the code and other resources that make up a Mac app. Application packages make it easy for users to move applications in their file systems. The contents of an application package are visible to users only when they Control-click the package and choose Show Package Contents. application font The font used as the default for user-created content. It is defined by each script system. application host A computer capable of running application instances. application ID A string that identifies an iPhone application or a set of iPhone applications from one vendor. They are similar to bundle identifiers. This is an example application ID: GFWOTNXFIY.com.mycompany.MyApp . application packaging Putting code and resources in the prescribed directory locations inside application bundles. Application package is sometimes used synonymously with application bundle . Application Kit See AppKit. application programming interface See API. application menu A menu that contains items that apply to the application as a whole, rather than to a specific document or other window. The application menu for the current active application appears immediately to the right of the Apple menu. application server A JBoss instance, which is started through Server Admin. application window The primary window of an application that is not document-based. Aqua The overall appearance and behavior of Mac apps. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 11 Glossary Aqua guidelines A set of guidelines that define the appearance and behavior of Mac apps. These guidelines bring a unique look to applications, integrating color, depth, clarity, translucence, and motion to present a vibrant appearance. If you use Cocoa or X11 to create your application’s interface, you get the Aqua appearance automatically. asymmetric keys A pair of related but dissimilar keys, one used for encrypting and the other used for decrypting a message or other data. See also public key cryptography. Compare symmetric keys. asynchronous (1) In Audio Queue Services, describes one of two ways to stop an audio queue. Asynchronous stopping happens after all queued buffers have been played or recorded. (2) In digital communications, a transmission method that does not require the clock frequency of the sender and receiver to be the same. Compare synchronous. ARB Architecture Review Board. This group oversees the OpenGL specification and extensions to it. arbitrary reference form In AppleScript, a reference form that specifies an arbitrary object in a container. asynchronous design approach The principle of organizing an application around blocks of code that can be run concurrently with an application’s main thread or other threads of execution. Asynchronous tasks are started by one thread but actually run on a different thread, taking advantage of additional processor resources to finish their work more quickly. architecture-specific build setting In Xcode, options for specific architectures, such as PowerPC or Intel. arrow keys The four keys on Apple keyboards (up, down, left, right) used to move the insertion point or change the selection. They can also be used with the Shift key to extend or shrink a selection. asynchronous launch A launch operation in which control returns immediately to the calling program, without waiting for the launched application to complete its launch sequence. Compare synchronous launch. ascent line An imaginary horizontal line that corresponds approximately to the tops of the uppercase letters in the font. Uppercase letters are chosen because, among the regularly used glyphs in a font, these are generally the tallest. asynchronous progress indicator A small round indeterminate progress indicator. It is usually visible only while active. ASCII American Standard Code for Information Interchange. A 7-bit character set (commonly represented using 8 bits) that defines 128 unique character codes. See also Unicode. ATF Anatomical Transfer Function. See HRTF. atom The basic unit of data in a movie resource, sprite, or other QuickTime data structure. There are a number of different atom types, including movie atoms, track atoms, and media atoms. There are two varieties of atoms: QT atoms, which may contain other atoms, and classic atoms, which do not contain any other atoms. See also classic atom, movie resource, QT atom, sprite. aspect ratio The width-to-height ratio of an image. For example, a 4:3 aspect ratio means the horizontal size is a third again wider than the vertical size. Every title on a DVD is authored for one of two aspect ratios: standard (4:3) or wide (16:9). assignment statement An AppleScript statement that assigns a value to a variable. Assignment statements use the copy or set commands. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 12 Glossary atom container A tree-structured hierarchy of QT atoms. See also QT atom. NSNumber objects. (2) In AppleScript, one of the two main descriptor data types that make up an Apple event. Not commonly used by scriptable Cocoa applications. (3) In an XML file, a name-value pair that specifies a single property for an element. (4) In Keychain Services, One data item, such as the name, type, date modified, account number, and so on, for a keychain item, other than the secret. The attributes associated with a keychain item depend on the class of the item. (5) In Entity-Relationship modeling, an identifiable characteristic of an entity. For example, lastName can be an attribute of an Employee entity. An attribute typically corresponds to a column in a database table. See also entity, session. atom ID A 32-bit integer that uniquely identifies an atom among other child atoms of the same parent atom. The root atom has an atom ID value of 0x0001. See also child atom, parent atom, root atom. atom type A 32-bit value that uniquely identifies the data type of an atom. It is normally an OSType value, rendered by four ASCII characters. An atom’s data type helps determine how the atom’s contents are interpreted. ATSUI Apple Type Services for Unicode Imaging. A technology that enables the rendering of Unicode-encoded text with advanced typographic features. ATSUI automatically handles many of the complexities inherent in text layout, including how to correctly render text in bidirectional and vertical script systems. audio file stream In Core Audio, a software object of type AudioFileStreamID, which represents data obtained from a TCP stream and supports manipulation of that data. See also TCP/IP. ATSUI style mask A byte-length mask with one bit set for each ATSUI-supported style to be applied. audio processing graph A representation of a signal chain comprising an interconnection of audio units. Also called an AUGraph or graph . Core Audio represents such an interconnected network as a software object of type AUGraph. Audio processing graphs must end in an output unit. See also audio unit. attach In OpenGL, an operation that establishes a connection between two existing objects. Compare bind. attached editor A text editor pane in the Xcode Project window. audio queue In Audio Queue Services, a software object of type AudioQueueRef, used for recording or playing back audio. There are two distinct types of audio queue. A recording audio queue (sometimes called an input audio queue ) typically accepts incoming audio from a hardware device and uses a callback function on its output side. A playback audio queue (sometimes called an output audio queue ) has a callback on its input side, and typically sends its output audio to external hardware. attaching The process of starting a debugging session on a process that’s already running and was not launched by Xcode. attachment A Core Foundation object associated with a video frame. This attachment, specified by a key-value pair, can hold any sort of information relevant to the frame, such as a timestamp. attribute (1) In key-value coding, a property that is a simple value, such as a scalar, string, or Boolean value, or to immutable objects such as NSColor and 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 13 Glossary audio queue buffer In Audio Queue Services, a data structure used as a container for transient blocks of audio data being played or recorded. An audio queue buffer is managed by the audio queue that owns it. server might verify a user’s identity by prompting the user for a name and password and comparing that information to the names and passwords in a database. In Kerberos authentication, the authentication server also looks up the user’s private key, generates a session key, and creates a TGT. See also ticket-granting server. audio session An iOS software abstraction that represents audio behavior for an application, in context, on an iPhone or iPod touch. An audio session has a category and can be active or inactive. authorization The process by which an entity such as a user or a server gets the right to perform a privileged operation. (Authorization can also refer to the right itself, as in “Bob has the authorization to run that program.”) Authorization usually involves first authenticating the entity and then determining whether it has the appropriate permissions. Compare authentication. audio session category See category. audio unit A Component Manager–based Simulator that adds an audio feature to a Mac app. Audio units can provide effects such as filtering and reverb, MIDI-based music synthesis, audio data format conversions, mixing, panning, sound generation, and audio playback. Unlike application-specific plug-ins, audio units are available systemwide. Multiple instances of a single audio unit can run simultaneously. authorization option A parameter or field that instructs the Security Server how to proceed with a request. Options include requesting preauthorization, requesting partial authorization, appending rights, and interacting with the user. AUGraph See audio processing graph. authorization reference A reference used by the Security Server to access an authorization session associated with a process. AUHAL An Apple-supplied audio unit used to interface with hardware input or output, so named because it interacts with the HAL (Hardware Abstraction Layer). Authorization Services An OS X API that facilitates fine-grain control of privileged operations, such as accessing restricted areas of the operating system and self-restricted parts of your Mac app. The Security Server uses policy-based decisions to authorize rights for users. authentication The act of verifying identity with something the user has, knows, or is. For example, a user knows information such as a name and password. The user may have something physical such as a smart card. The identity can be something the user is—a physical feature such as a fingerprint or retinal scan. Authentication may require two or more forms of identification. Compare authorization, identification. authorization tag A data field in an access control list (ACL) that specifies an operation that can be done with that keychain item, such as decrypting or authenticating. auto-key event An event indicating the user has held a key down for a certain amount of time. authentication server A server that has access to a store of authentication information and that can authenticate users. For example, an authentication 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 14 Glossary automatic guide An alignment tool that shows the spacing required to meet the appropriate interface guidelines for the target platform. This type of guide appears and disappears automatically. azimuth In surround sound and immersive audio, the real or apparent horizontal angle of an audio source referenced to a line drawn from the listener’s head to a point directly ahead of the listener. Automator action A loadable bundle that performs discrete tasks that users can link together in a workflow using the Automator application. background The part of a glyph bitmap that surrounds the pixels that constitute the glyph itself. background color The color of the background behind a sprite or other image. auto-repeat A feature that lets users produce numerous instances of the same character by holding down its key rather than pressing the key over and over. Users can make adjustments to this feature in Keyboard & Mouse preferences. background selection A selection in an inactive window. In Aqua, such selections are in the secondary highlight color. backing store A file in which the Virtual Memory Manager stores the contents of unneeded pages of memory. autosizing behavior In Interface Builder, a mechanism that automatically adjusts the size and position of views during resize operations based on a set of options. See also spring, strut. backtrace A list of the handlers that have been invoked at any point in a script execution. Each handler is listed as a call frame. AV/C Audio/Video Control. A standard, published by the IEEE, that provides a music and audio device command protocol over FireWire (IEEE 1394) connections. band A horizontal strip from an image. For raster printing, the image corresponding to the page raster is broken into strips of manageable size. average bit rate Describes an encoded audio representation that, while allowing variations in bit rate from frame to frame, maintains a specific average bit rate over a long time interval (typically between 10 and 60 seconds). You can use ABR-savvy encoders to fit a recording into a predetermined file size. Compare constant bit rate, variable bit rate. bandwidth (1) In analog audio, the width of a frequency band for a transmission channel, from a lower to an upper frequency limit. The limits are defined in terms of signal attenuation, in decibels, relative to the level at the center of the band. See also decibel. (2) In digital data transmission, the available data throughput for a transmission channel. Digital bandwidth is typically expressed in terms of bits or bytes per second. See also bit rate. AVI Audio Video Interleave. A chunk-based, container file format defined by Microsoft Corporation in 1992. AVI is a specialization of the RIFF format, which in turn is based on IFF. base class In C++, the class from which another class (a subclass) inherits. It can also be used to specify a class from which all classes in a hierarchy ultimately derive (also known as a root class ). axial gradient A fill that varies along an axis between two defined end points. All points that lie on a line perpendicular to the axis have the same color value. Also called a linear gradient . 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 15 Glossary baseline An imaginary horizontal line that coincides with the bottom of each character in a font, excluding descenders (tails on letters such as p ). bidirectional script system A script system in which text is generally right-aligned with most characters written from right to left, but with some left-to-right text as well. Arabic and Hebrew are bidirectional script systems. baseline delta The distance (in points) between a baseline and y = 0; sometimes referred to as delta-y. See also baseline type. bidirectional text The combination of text with both left-to-right and right-to-left directions within a single line of text. baseline type The kind of baseline used with a particular kind of text. binary operator An operator that derives a new value from a pair of values. base SDK A project setting that specifies the default SDK to use when building the project’s targets. Targets can override this setting with the iOS Deployment Target build setting. bind An operation that creates a new object and then establishes a connection between that object and a rendering context. base URL For documentation sets, an alternate location for documentation nodes whose documentation files reside on the web. The default location is in the installed documentation set bundle or its fallback web location. binding A two-way connection between the objects of a data model and the views of a user interface. Cocoa bindings provide automatic synchronization between data objects and the views displaying information about those objects. basic animation A simple animation from a start value to a target value. binding information The information maintained in the Launch Services database about the kinds of documents and URLs an application is capable of opening. batch faulting An feature that allows you to reduce round trips to the database by firing multiple faults in a single fetch. See also faulting. binding preference A preference set by the user specifying the application in which to open a given document or URL. beat The basic time unit of a musical piece; typically, the bottom number in a time signature. Core Audio’s music player uses the notion of beats in the tempo track. binding rules The rules used by Launch Services to determine an item’s default application according to the binding information in the Launch Services database. best size The optimum size for displaying the contents of a window. bevel button A button with a beveled edge that gives the button a three-dimensional appearance. biometric identifier A measurement of biological matter used for identification—for example, fingerprints, retinal scans, and face recognition. Bézier curve A cubic equation originally developed by Pierre Bézier. In typography, used to define the shape of a glyph. bit depth The number of bits used to describe something, such as an audio sample or the color of a pixel. Each additional bit in a binary number bidi See bidirectional script system. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 16 Glossary doubles the number of possibilities. For audio samples, bit depth along with some other factors, determines the dynamic range of a digital system. BOM Bill of materials. A file in an installer package used by the Installer to determine which files to install, remove, or upgrade. It contains all the files within a directory, along with information about each file such as the file’s permissions, its owner and group, size, its time of last modification, a checksum for each file, and information about hard links. bitmap (1) A rectangular array (or raster) of pixels, each pixel representing a point in an image. Bitmap images are also called sampled images . (2) A data structure that represents the positions and states of a corresponding set of pixels. Bonjour Apple’s technology for zero-configuration networking. Bonjour enables dynamic discovery of services over a network. bitmap graphics context A bit-based offscreen drawing destination. bookmark A data object that specifies the current media position during playback of a DVD. Because the byte length of a bookmark is known, you can save the bookmark in a file for later use. bitplane A rectangular array of pixels. bit rate The data rate (or bandwidth) of a digital channel, in bits per second. boolean A logical truth value. blend mode The way Quartz combines the foreground painting with the background painting. Boolean expression An expression whose value can be either true or false. blit Slang for copying an image from memory to the screen. Boolean searching Matching of a query string to indexed terms using Boolean (logical) operators such as AND and OR between query terms, optionally employing grouping for precedence using parentheses. The entire query expression is matched. See also search. blitting The process of moving bits from a back buffer to an onscreen location. Blitting is not necessary (not recommended) when using Quartz. blocked The state where an application or thread is waiting for some event or action to occur. While blocked, that particular code path uses no processor time. bottomline input A type of input method in which the user enters text in a small window, called a floating input window , that appears near the bottom of the screen. Compare inline input. block object A C construct for encapsulating inline code and data so that it can be performed later. You use blocks to encapsulate tasks you want to perform, either inline in the current thread or on a separate thread using a dispatch queue. bottom-side bearing The white space between the bottom of the glyph and the visible ending of the glyph. bold text The font style that Xcode uses in panes of Project and Target Info windows to indicate build settings specified at the current level. Build settings that are not in bold text are specified at lower layers. bounding box The smallest rectangle that entirely encloses the pixels or outline of a glyph. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 17 Glossary breakpoint action In Xcode, an action to perform when a program reaches a certain point in its execution, such as logging output to the console. The default breakpoint action is to pause program execution. build client The computer that performs a build operation. This is the computer that runs the Xcode or the xcodebuild instance that carries out the build command. build configuration A named set of build settings that tells Xcode how to build a product. The typical build configurations are Debug and Release, but you can define additional build configurations. See also build setting. browse mode In Xcode, a mode of the Documentation window in which you can traverse a hierarchy of categories in a documentation set until you get to a list of documents. Compare search mode. build configuration file A file that contains Xcode build setting definitions. You can use it to share a set of build setting definitions among all the individuals working on a team. You can also use a configuration file to quickly configure targets and projects with common build setting definitions. browser view The part of the Documentation window that displays the documentation category hierarchy. BSD Berkeley Software Distribution. Formerly known as the Berkeley version of UNIX, BSD is now simply called the BSD operating system. The BSD portion of Darwin is based on 4.4BSD Lite 2 and FreeBSD, a flavor of 4.4BSD. build directory The file-system directory in which Xcode stores built products. It is usually the build folder in the project folder. buffer A block of memory dedicated to storing a specific kind of data. For example, Core Audio uses buffers to supply audio to, and receive audio from, audio units. In graphics, a buffer stores data such as depth values and color index values. Build pane The pane in the Xcode Project and Target info windows that lets you view and edit build settings at the target and project levels. build phase In Xcode, a set of operations performed on a group of files as part of building a product. buffer pool A collection of preallocated buffers that can be used over and over. Keeping a pool of buffers available requires less overhead than allocating and deallocating a buffer each time it is needed. Build Results window A view that displays a detailed account of the progress of a build, including each step of the build process and the full output of the build system. It can take you directly to the source of any errors or warnings. buffer queue In Audio Queue Services, an ordered list of audio queue buffers used by an audio queue. See also audio queue, audio queue buffer. build server A computer that a build host uses to perform compilation tasks. Build servers do not need to run Xcode or xcodebuild to aid a build host, but they must at least be running the same version of the Mac OS as the build server. buffered window A window with a memory buffer into which all drawing is rendered. All graphics are first drawn in the buffer, and then the buffer is flushed to the screen. build The process Xcode uses to create a target. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 18 Glossary build set In Xcode, the host names of build servers to which a build client distributes compilation tasks. To distribute a build, you must define at least one build set on the build client, or use the Bonjour set when available. bundle information property list A collection of key-value pairs giving information about an application, stored in a file named Info.plist in its application bundle. bus A transmission path on which signals can be dropped off or picked up by devices attached to it. Only devices addressed by the signals pay attention to them; the others discard the signals. Buses exist both within the CPU and connect it to physical memory and peripheral devices. Examples of I/O buses on Darwin are PCI, SCSI, USB, and FireWire. For its meaning in Core Audio, see element. build setting In Xcode, a variable that contains the information for building a product. For each operation performed in the build process—such as compiling Objective-C source files—build settings control how that operation is performed. build setting name In Xcode, a label that identifies a build setting. It is similar to the names of environment variables in a command shell. bus master A program, usually in a separate I/O controller, that directs traffic on the computer bus or input/output paths. The bus master actually controls the bus paths on which the address and control signals flow. DMA is a simple form of bus mastering where the bus master controls I/O transfers between a device and system memory and then signals to the CPU when it has done so. See also DMA. build setting specification The information Xcode uses to determine the value of a build setting at build time. build setting title The label used to display the build setting in the Xcode user interface. build style A methodology of creating a product from a target in Xcode. Development and Deployment build styles use different methodologies. business logic The rules associated with the data in a database that typically encode business policies. An example is automatically adding late fees for overdue items. bullet In the Window menu, indicates that the document has unsaved changes. button See bevel button, icon button, push button, radio button. bundle A directory in the file system that typically stores executable code and the software resources related to that code. Applications, plug-ins, frameworks, and kernel extensions are types of bundles. Except for frameworks, bundles are file packages, presented by the Finder as a single file instead of a folder. See also kernel extension. bytecode Computer object code that is processed by a virtual machine. The virtual machine converts generalized machine instructions into specific machine instructions (instructions that a computer’s processor can understand). Bytecode is the result of compiling source language statements written in any language that supports this approach. The best-known language today that uses the bytecode and virtual machine approach is Java. In Java, bytecode is contained in a binary file with a .class bundle identifier A unique identifying string used to locate an application’s bundle at runtime. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 19 Glossary suffix. (Strictly speaking, “bytecode” means that the individual instructions are one byte long, as opposed to PowerPC code, for example, which is four bytes long.) See also VM. Carbon Printing Manager A collection of system software routines that can be used by a Carbon application. It replaces the Mac OS 9 Printing Manager. byte offset The indexed position of a 2-byte Unicode character in a text buffer, starting at zero for the first character. Sequential values for character offset correspond to the storage order of the characters. Compare edge offset. caret A vertical or slanted blinking bar, appearing at the caret position in the display text, that marks the point at which text is to be insert or deleted. See also split caret. caret angle The angle of a caret or of the edges of a highlight. The caret angle can be perpendicular to the baseline or parallel to the angle of the style run’s text. CA digital certificate. In order for a digital certificate to be trusted, the certification authority must be a trusted organization that authenticates an applicant before issuing a certificate. caret position A location onscreen, typically between glyphs, that relates directly to the offset (in memory) of the current text insertion point in the source text. At the boundary between a right-to-left and left-to-right direction run on a line, one character offset may correspond to two caret positions, and one caret position may correspond to two offsets. cache A special type of memory that is substantially faster than typical main memory (RAM). When a program asks the CPU to read or write data in memory, it first checks to see whether this data is stored in cache memory (because it will be faster to retrieve or write). Cache sizes are usually quite small though, (under 2 MB) so in order to make use of it, the data must be small enough to fit in the cache. caret type A designation of the behavior of the caret at direction boundaries in text. See also dual caret. CAF Core Audio Format. Apple’s universal audio file format. CAF files are chunk-based and can contain AAC, MP3, and PCM audio data, among many other audio data formats, as well as MIDI data. See also chunk, PCM. category Also called audio session category . In iOS, a collection of audio behaviors for an application. For example, a category specifies whether an application intends to mix its audio with other applications or silence them. You specify your application’s category after initializing its audio session. call frame The information about a handler call, including its calling parameters and local variables. call stack A collection of stack frames that positions the most recent calls on the top of the stack. CBR Constant bit rate. A data encoding scheme that can be used to stream audio data over a channel at a constant bit rate while supporting real-time decoding. In most cases, packet size is constant in CBR streams. In the case of constant bit rate AAC streams, packet size may vary slightly. Some Carbon An OS X application environment that uses procedural programming interfaces derived from earlier versions of the Mac OS. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 20 Glossary encoding schemes, such as PCM, support only CBR encoding. Compare average bit rate, variable bit rate. See also simple message. certificate chain A sequence of related digital certificates that are used to verify the validity of a digital certificate. Each certificate is digitally signed using the certificate of its certification authority ( CA). This creates a chain of certificates ending in an anchor certificate. CDSA Common Data Security Architecture. An open software standard for a security infrastructure that provides a wide array of security services, including fine-grained access permissions, authentication of users, encryption, and secure data storage. CDSA has a standard application programming interface, called CSSM. In addition, OS X includes its own security APIs that call the CDSA API for you. See also CDSA plug-in. certificate extension A data field in a digital certificate containing information such as allowable uses for the certificate. certificate signing request See source text. certificate subject The entity associated with the public key that is in the certificate. CDSA plug-in A software module that connects to CDSA through a standard interface and that implements or extends CDSA security services for a particular operating system and hardware environment. Certificate, Key, and Trust Services An API you can use to create, manage, and read certificates; add certificates to a keychain; create encryption keys; and manage trust policies. In iOS, you can also use this API to encrypt, decrypt, and sign data. ceiling The maximum allowable signal level in an audio system. The ratio of the ceiling to the noise floor is the dynamic range. Also called dynamic ceiling . certification authority See CA. center equalization Placement of controls in a window so that overall, they are visually balanced across an imaginary vertical line in the center of the window. CFHTTP An API that you can use to create, serialize, deserialize, and manage HTTP protocol messages, including secure HTTPS messages. This component lets you add authentication information to a message. CFHTTP is a component of CFNetwork and is built on top of CFStream. center justification The placement of controls or text where every item is centered on an imaginary vertical line in the center of a window. CFM Code Fragment Manager. The library manager and code loader for processes based on PEF (Preferred Executable Format) object files (in Carbon). certificate See digital certificate. CFNetServices An API that allows you to use Bonjour. Bonjour enables applications to discover services that are available on the network and find all access information (such as name and IP address) needed to use each service. CFNetServices is a component of CFNetwork. This component has no security features. Certificate Assistant A utility available through the Keychain Access Utility that can be used to create certificates and keys, request certificates from a certificate authority, and evaluate certificates. certificate authority See CA. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 21 Glossary CFNetwork A high-level API used for creating, sending, and receiving serialized messages over a network. CFNetwork is built on top of Secure Transport, and so can use the Secure Transport and TLS secure networking protocols. CGLs framework Core OpenGL framework. The Apple framework for using OpenGL graphics in Mac apps (Cocoa or Carbon) that need low-level access to OpenGL. CGLayer An offscreen graphics context, introduced in OS X v10.4, suited for high-quality offscreen rendering of content that you plan to reuse. CFStream An API that creates and manages the read and write streams that CFHTTP depends on. CFStream is a component of CFNetwork and is built on top of Secure Transport. You can specify a SSL or TLS protocol version to encrypt and decrypt the data stream. channel A discrete track of audio. A monaural recording or live performance has exactly one channel. A stereo recording or live performance has two channels. A multitrack recording or performance can have any number of channels. Between audio units, a connection has one or more channels. See also channel layout. CFString An object that represents an array of Unicode characters ( UniChar ) along with a count of the number of characters. Unicode-based strings in Core Foundation provide a solid basis for internationalizing the software you develop. Unicode makes it possible to develop and localize a single version of an application for users who speak most of the world’s written languages, including Russian (Cyrillic), Arabic, Chinese, and Japanese. Although conceptually CFString objects store strings as arrays of Unicode characters, in practice they often store them more efficiently. The memory a CFString object requires is typically about the same or even less than that required by a simple UniChar array. channel layout A description of the playback roles for the channels in an audio recording. For example, in a stereo recording, channel 1 has the role of “left front” and channel 2 has the role of “right front.” chapter (1) In DVD-Video, a division of a title. Technically called a part of title (PTT). (2) A method of organizing different scenes of a movie for easy navigation and access. DVDs are indexed by chapter, similar to the way a CD has a track. DVD players allow you to skip to a particular chapter or scene. CG The prefix used for functions in the Quartz API. See also Core Graphics. chapter list A set of named entry points into a movie, presented to the viewer as a text list. CGI Common Gateway Interface. A standard for interfacing external applications with information servers, such as HTTP or web servers. character An atomic unit of content for text data. A character is an abstract entity without any particular appearance; characters include letters, digits, punctuation, and symbols. Compare character code, glyph. CGI adaptor An HTTP adaptor that uses the Common Gateway Interface (CGI) to translate requests from an web server into requests to an application instance, and responses from an application instance to responses to the web server. The web server creates a CGI process to handle each request. character clusters A collection of characters treated as individual components of a whole, including a principal character plus attachments in memory. For example, in Hebrew, a cluster may be composed of 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 22 Glossary a consonant, a vowel, a dot to soften the pronunciation of the consonant, and a cantillation mark. choice requirement In PackageMaker, a test that compares the value of a system property (such as the amount of random-access memory available) with a value. Choice requirements determine the value of a choice’s user-interface properties: selected, actionable, and visible. character code A numerical representation of a character. Each writing system or language has one or more character encodings—tables that relate character codes to the characters they represent. choice requirement editor The area of a PackageMaker project window that allows packagers to specify a choice requirement (and how it affects the value of the choice’s user-interface properties). See also choice requirement. character encoding A conversion table for interpreting a specific character set. See also text encoding. character key A key that sends a character to the computer. Character keys include letters, numbers, punctuation, and the Space bar, and nonprinting characters such as Tab and Return. chunk (1) In Core Audio, a linear block of data consisting of a short, descriptive header followed by the described data. A chunk-based file is an on-disk file laid out as a series of chunks. (2) In QuickTime, A collection of sample data in a media structure. Chunks, which may contain one or more samples, allow optimized data access. Chunks in a media structure may have different sizes, and the samples within a chunk may have different sizes. character rendering The process of preparing characters for display, taking into account line direction, contextual rules, and character reordering. For example, the formation of ligatures and diphthongs occurs during the display of text. chunk data section The data content of a synchronous. The format of the data depends on the chunk type, as specified in the chunk header. checkbox A control for an option that must be either on or off. checkmark In the Window menu, a checkmark appears next to the active document’s name. In other menus, checkmarks can be used to indicate that the setting applies to the entire selection. Checkmarks can be used for mutually exclusive attribute groups or for accumulating attribute groups. chunk header The descriptive, metadata section at the start of a synchronous. Each element of information in a chunk header is called a field . CIFS Common Internet File System. A file-sharing protocol used widely on Windows and UNIX systems. CIFS is an extension of the SMB protocol. CIFS has been given to the Internet Engineering Task Force (IETF), making it an Internet standard. Unlike SMB, CIFS runs only over TCP/IP. See also Samba. chevrons See double angle brackets. child atom A QT atom inside a container atom, which is its parent atom. See also container atom, parent atom, QT atom. ciphertext Text or other data that has been encrypted. Compare plaintext. child script object A script object that inherits properties and handlers from another object, called the parent. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 23 Glossary claim To declare to Launch Services that an application is capable of opening documents or URLs of a given type. click-through A property of some controls that enables user to activate them in an inactive window. Whether a control supports click-through depends on the context. class (1) In object-oriented languages such as Objective-C and Java, a prototype for a particular kind of object. A class definition declares instance variables and defines methods for all members of the class. Objects that belong to the same class have the same types of instance variables and have access to the same methods (included the instance variables and methods inherited from superclasses). (2) In AppleScript, a category for objects that share characteristics such as properties and elements and respond to the same commands. client (1) A driver object that consumes services of some kind supplied by its provider. In a driver stack, the client in a provider/client relationship is farther away from the Platform Expert. See also provider. (2) In source control management, the program a developer uses to interact with the repository. clip Prepackaged “mini” Quartz Composer compositions that you can drag into a composition and customize for your own use. classic atom A QuickTime atom that contains no other atoms. A classic atom, however, may contain a table. An example of a classic atom is an edit list atom, containing the edit list table. Compare QT atom. Clipboard A per-user server (also known as the pasteboard ) that enables the transfer of data between applications, including the Finder. This server is shared by all running applications and contains data that the user has cut or copied, as well as other data that one application wants to transfer to another, such as in dragging operations. Data in the Clipboard is associated with a name that indicates how it is to be used. You implement data-transfer operations with the Clipboard using Core Foundation Pasteboard Services or the Cocoa NSPasteboard class. See also pasteboard. Classic Event Manager The event handling interface used in Mac OS applications before the Carbon Event Manager. The Classic Event Manager often required a certain amount of polling of the event queue. clip coordinates In OpenGL, the coordinate system used for view-volume clipping. Clip coordinates are applied after applying the projection matrix and prior to perspective division. class property In WebObjects, a field in an enterprise object that meets two criteria: It’s based on an attribute in your model, and it can be fetched from the database. Class property can refer either to an attribute or to a relationship. clipped movie boundary region The region that combines the union of all track movie boundary regions for a movie, which is the movie’s movie boundary region, with the movie’s movie clipping region, which defines the portion of the movie boundary region that is to be used. See also movie boundary region, movie clipping region. class description A scripting definition file (sdef ) entry that describes a scriptable class, including its attributes and relationships and the KVC keys that Cocoa scripting uses to gain access to its values. When the sdef is loaded, the information is stored in an instance of NSScriptClassDescription . clean In Xcode, to remove all the product files, as well as any object files (.o files) or other intermediate files created during the build process. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 24 Glossary clipping (1) In OS X, data dragged from an application to the Finder desktop. (2) In graphics, the process of defining the boundaries of a graphics area. (3) In audio, distortion of a waveform resulting from the limiting of signal amplitude to a specific level. See also distortion. Cocoa framework An object-oriented application framework, consisting of a collection of advanced object-oriented APIs. The Cocoa framework is made up of the AppKit and Foundation frameworks. Also referred to simply asCocoa. Cocoa scripting In the Cocoa application framework, the support for creating scriptable applications. Cocoa scripting includes classes, categories, and scriptability information, which together support much of AppleScript’s Standard suite. clipping area A path used to constrain the drawing of other objects within its bounds. clock (1) In Mach, an object used to abstract time. (2) The regular, periodic signal in a digital audio system used to pace audio recording and playback. clock drift In audio, the deviation, over time, of one system output relative to another, due to differing counting rates. Clock drift interferes with synchronization. Cocoa user interface class A class that supports a user interface item. The Application Kit provides many of these classes; for example, NSButton and NSBrowser are Cocoa user interface classes provided by the Application Kit. clock recovery In audio, extracting and reconstructing timing information from a data stream. Cocoa user interface object An instance of a Cocoa user interface class. codec (coder/decoder) A generic term applied to, among other things, lossy and lossless audio compression technologies implemented in hardware or software. Encoded data can be wrapped in a file format appropriate for the data, or decoded from such a file format. For example, the MP3 file format is a wrapper that can hold perceptually encoded audio data. close button A window control (the red button that appears in the upper left) that users can click to close the window. CMP Container-managered persistence. An enterprise bean persistence model in which the J2EE container is responsible for persisting enterprise-bean instances to a data store and populating the fields of enterprise-bean instances when they are retrieved. code completion In Xcode, a shortcut that automatically suggests likely completions as you type an identifier or a keyword. The suggestions are based on the text you type and the surrounding context within the file. Cocoa An advanced object-oriented development platform in OS X. Cocoa is a set of frameworks used for the rapid development of full-featured applications in the Objective-C language. It is based on the integration of OpenStep, Apple technologies, and Java. code focus A feature of the Xcode text editor that highlights the scope of the selected source code. code folding A feature of the Xcode text editor that hides code you don’t want to see. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 25 Glossary code fragment In the CFM-based architecture, a code fragment is the basic unit for executable code and its static data. All fragments share fundamental properties such as the basic structure and the method of addressing code and data. A fragment can easily access code or data contained in another fragment. In addition, fragments that export items can be shared among multiple clients. A code fragment is structured according to the Preferred Executable Format (PEF). color-lookup table A table of values used to map color indexes into actual color values. Code Sense In Xcode, a process that maintains an index to a rich store of information about the symbols defined in a project. Xcode uses this information as the basis for a number of features that let you browse the symbols in your project, view the class hierarchy of projects that use an object-oriented programming language, and search your project for symbol definitions. column In a relational database, the dimension of a table that holds values for a particular attribute. For example, a table that contains employee records might have a column titled “LAST_NAME” that contains the values for each employee’s last name. See also attribute. ColorSync An industry-standard architecture for reliably reproducing color images on various devices (such as scanners, video displays, and printers) and operating systems. color well A small rectangular or square control used to apply a color selection. The color of the control indicates the currently selected color. column view A control that displays textual listings of hierarchical data in vertical columns. Navigation between columns reveals levels of the hierarchy. code signing The addition of a digital signature to an application or block of code. combination box A text entry field combined with a drop-down scrolling list. Combo boxes are useful for displaying a list of likely choices while still allowing the user to type in an item not in the list. coefficient The number that is multiplied to each of the factors in a polynomial equation. For example, in the equation x2 + 2x + 1 , the coefficients are 1 , 2 , and 1 . command In AppleScript, a word or phrase in a script that requests an action. For example, a script can send a stop command to a progress indicator object. Compare target dependency. See also SOAP engine. coercion The process of converting an object from one class to another. For example, an integer value can be coerced into a real value. Also, the software that performs such a conversion. Also known as object conversion . command description A scripting definition file (sdef ) entry that describes the characteristics of an AppleScript command, including argument names (if any), command result type (if any), AppleScript command name, and name of the Objective-C class Cocoa instantiates to perform the command. When the sdef is loaded, the information is stored in an instance of NSScriptCommandDescription . color space A one-, two-, three-, or four-dimensional environment whose components (or channels) represent intensity values. For example, RGB space is a three-dimensional color space whose stimuli are the red, green, and blue intensities that make up a given color; and red, green, and blue are color channels. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 26 Glossary command gate A mechanism that controls access to the lock of a work loop, thereby serializing access to the data involved in I/O requests. A command gate does not require a thread context switch to ensure single-threaded access. IOCommandGate event-source objects represent command gates in the I/O Kit. compatibility version One of two numbers used to track minor version information in a framework. This number marks changes to the public interfaces. The compatibility version typically lags behind the current version. Compare current version. compile In AppleScript, to convert a script from the form typed into a script editor to a form that can be used by AppleScript. The process of compiling a script includes syntax and vocabulary checks. A script is compiled when you first run it and again when you modify it and then run it again, save it, or check its syntax. command ID A four-character code that uniquely identifies a menu item or control. Note that a menu item and a control can share the same command ID. command pop-down menu A menu that contains commands and appears in a window rather than in the menu bar. Use of this control is limited to cases where the window is shared among multiple applications and the menu contains commands that affect the window’s contents. A closed pop-down menu always displays the same text, which is the menu title. Pop-down menus have a single, downward-pointing triangle. compiled script The form to which an AppleScript script is converted when you compile it. completeness In OpenGL, a state that indicates whether a framebuffer object meets all the requirements for drawing. completion list A list that Xcode builds for a typed token and that you can display when using code completion. See code completion. command-line utility A tool without a graphical user interface, typically used in the command-line environment. component (1) A part of a software product that resides at a distinct location in the file system. See also component package. (2) A plug-in whose interface is defined by the Component Manager. For example, an audio unit is a component. (3) An object (of the WOComponent class) that represents a webpage or a reusable portion of one. comment Text that remains in a script after compilation but is ignored by AppleScript when the script is executed. commit To publish changes in an Xcode project to a repository. compact To make a search index smaller by removing unused bits. Over time, as documents get added to and removed from an index, the index’s disk or memory footprint may grow due to fragmentation. Search Kit includes APIs to check for fragmentation and to compact an index. See also fragmentation. component package An installation package whose payload is one of the components of a product. See also product package. component package editor The area of a PackageMaker project window that specifies packaging and installation information about a product component. This editor is displayed when a component is selected in the Contents pane in the project window. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 27 Glossary composite SDK A group of additional SDKs used by a target. Xcode creates and caches the composite at build time. concrete type Defines, in information property lists, specific characteristics of a type of document, such as extensions and HFS+ type and creator codes. Each concrete type has corresponding abstract types. See also abstract type. composite value In AppleScript, a value that contains other values. Lists, records, and strings are examples of composite values. concurrent operation An operation object that does not perform its task in the thread from which its start method was called. A concurrent operation typically sets up its own thread or calls an interface that sets up a separate thread on which to perform the work. compositing A method of overlaying separately rendered images into a final image. It encompasses simple copying as well as more sophisticated operations that take advantage of transparency. composition In Quartz Composer, a collection of interconnected patches that describe a data flow. condition A construct used to synchronize access to a resource. A thread waiting on a condition is not allowed to proceed until another thread explicitly signals the condition. composition repository In Quartz Composer, a central location for storing compositions. Any application can, using the Quartz Composer framework, query the repository for specific types of compositions or browse the repository to see what’s available. conditional build setting In Xcode, setting values that apply only when one or more conditions are met (for example, the product is being built using a particular SDK). Xcode uses these definitions when generating executable code for a particular architecture or for a particular variant of the product. compound statement An AppleScript statement that occupies more than one line and contains other statements. A compound statement begins with a reserved word indicating its function and ends with the word end . See also simple statement. conditional statement See if statement. condition variable A wait queue with additional locking semantics. When a thread sleeps, waiting for some event to occur, it releases a related lock so that another thread can cause that event to occur. When the second thread posts the event, the first thread wakes up, and, depending on the condition variable semantics used, either takes the lock immediately or begins waiting for the lock to become available. compression See data compression, level compression. compressor Hardware or software that implements either data compression or level compression. A data compressor, along with its corresponding decompressor, is sometimes referred to as a codec . configuration file See build configuration file. concatenation In Quartz 2D, an operation that combines two matrices by multiplying them together. configuration unit In Xcode, a group of configuration files joined together by #include directives. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 28 Glossary connection In Core Audio, a hand-off point for audio data entering or leaving an audio unit. A connection has one or more channels. See also channel. container atom An atom that contains other atoms, possibly including other container atoms. containment hierarchy A hierarchy of event targets that determines which handler is to be called to process an event. Events are initially sent to the innermost (or lowest) relevant target in the hierarchy. If the handler associated with that event target does not handle the event (or if no handler exists), then the event is propagated to the next target in the hierarchy. If no handler in the hierarchy processes the event, the default handler is called. connections panel In Interface Builder, a panel that appears as needed to display the connection status of outlets and actions. considering statement In AppleScript, a control statement that lists a specific set of attributes to be considered when AppleScript performs operations on strings or sends commands to applications. content pane In either browse mode or search mode, a view that displays category information or a document page. console (1) A text-based login environment that also displays system log messages, kernel panics, and other information. (2) A special window in OS X that displays messages that would be printed to the text console if the GUI were not in use. This window also displays output written to the standard error and standard output streams by applications launched from the Finder. content region The portion of the window below the title bar. The content region can contain document content or controls. content view In Mac apps, the view object that acts as the root for all other views in the window. In iOS applications, the portion of an iPhone window that displays the application’s custom content. Each content view may be represented by one or more actual views and typically presents a single screen’s worth of application content. Console An application that displays the console window. constant A reserved word with a predefined value. constant bit rate See CBR. context (1) In OpenGL, a set of OpenGL state variables that affect how drawing is performed for a drawable object attached to that context. Also called a rendering context . (2) In the OS X printing system, a pointer to a custom data structure that contains state information shared among the functions in a printing dialog extension. consumer (1) In Quartz Composer, a patch that renders a result to a destination. (2) In WebObjects, an application that executes a web service operation by sending a SOAP message to a web service provider. container (1) A file-based enclosure for a software product that facilitates delivery to its users. Disk images installation packages, and ZIP archives are the most popular product containers. (2) In AppleScript, a file-based enclosure for a product that facilitates delivery to its users. Disk images installation packages, and ZIP archives are the most popular product containers. contextual features Features that are applied to a glyph depending on the glyph’s position relative to adjacent glyphs. Compare noncontextual features. contextual form An alternate form of a glyph whose use depends on the glyph’s placement in a word. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 29 Glossary contextual menu A menu that appears when the user presses the Control key and clicks an interface item. A contextual menu provides convenient access to frequently used commands associated with the item. control port In Mach, access to the control port allows an object to be manipulated. Also called the privileged port . See also name port, port. control reference A pointer to an opaque data structure that describes a control’s properties. You manipulate a control by means of its control reference. contiguous highlighting Highlighting that consists of a single, contiguous shape across direction boundaries, even when it does not exactly match the selection range to which it corresponds. Compare discontinuous highlighting. control statement A statement that causes AppleScript to exit the current handler and transfer execution to the handler with the same name in the parent. A continue statement can also be used to invoke an inherited handler in the local context. continuation character In AppleScript, a character used in Script Editor to extend a statement to the next line. With a U.S. keyboard, you can enter this character by typing Option-l (lowercase L). converter A module used by the printing system to convert a document description from one document format to another. continue statement In AppleScript, a statement that controls when and how other statements are executed. AppleScript defines standard control statements such as if, repeat, and while . convolution A common image processing technique that changes the intensities of a pixel to reflect the intensities of the surrounding pixels. Using convolution, you can get image effects like blur, emboss, and sharpen. continuous selection A selection that includes all content between the anchor point and the active end. cookie See magic cookie. continuous style In MLTE, a style value that is constant over an entire selection range. cooperative multitasking A multitasking environment in which a running program can receive processing time only if other programs allow it; each application must give up control of the processor cooperatively in order to allow others to run. Mac OS 9 is a cooperative multitasking environment. See also preemptive multitasking. control A graphic object that causes instant actions or visible results when the user manipulates the object. Standard controls include buttons, scroll bars, checkboxes, sliders, and pop-up menus. control layer The classes in the package com.webobjects.eocontrol , which include EOEditingContext and EOEnterpriseObject . You use classes in this layer to fetch, create, manage, and save persistent data to a data source. coordinate scale In Core Audio, for a panner unit, a parameter that specifies the maximum value for the distance parameter, in meters. Copies & Pages pane A pane in the Print dialog that lets the user set the number of copies and the range of pages to be printed. controller object An object that manages the interactions between an application’s data objects and the objects that display that data. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 30 Glossary CopyBits A QuickDraw function that has no direct replacement in Quartz, primarily because Quartz does not use a bit-based graphics model, as QuickDraw does. Core MIDI An OS X framework for controlling and communicating with MIDI devices. corpora Plural form of corpus. corpus A collection of one or more documents, typically related, and available to an information retrieval system. Plural: corpora. copy-on-write A delayed copy optimization used in Mach. The object to be copied is marked temporarily read-only. When a thread attempts to write to any page in that object, a trap occurs, and the kernel copies only the page or pages that are actually being modified. See also thread. counter The oval in glyphs such as “p” or “d”. creator signature In the Macintosh file system, a four-character code that identifies the application to which a file belongs. Core Audio A set of iOS and OS X frameworks that provides audio services (depending on the platform) that include recording, playback, synchronization, signal processing, format conversion, panning and surround sound, hardware abstraction, and others. credential Proof of user authentication. It’s used by the Security Server. When the Security Server authenticates a user, it creates a credential as part of the authorization session. Core Audio Format See CAF. credentials Data that can be used to identify, authenticate, or authorize an entity. For example, a user name and password constitute authentication credentials. A Kerberos ticket, consisting of an encrypted session key and other information, is an identification credential. In Kerberos version 5 and later, tickets can also carry authorization information. Core Data A technology for managing structured data in your application. The data model of a Core Data application is built on a schema that defines one or more entities and their properties and the relationships between those entities. At runtime, Core Data manages the data for those entities using a database or other structured form of data store. critical section A portion of code that must be executed by only one thread at a time. Core Foundation URL reference A data object of type CFURLRef specifying a URL. cross-development Creating software that can be deployed on, and take advantage of features from, specified versions of OS X, including versions different from the one you are developing on. Core Graphics The name of the framework (CoreGraphics.framework) in which the Quartz API resides. The Quartz API is sometimes referred to as the Core Graphics API. cross-project reference A reference from the project that contains an application to a project that contains a framework. It lets you access the targets and products of the referenced project from your current project. Core Image An image processing programming interface that is part of the Quartz Core framework. Core Image filter An image processing routine provided by the Core Image framework. Core Image filters are automatically read into Quartz Composer and made available as patches. cross-stream kerning The automatic movement of glyphs perpendicular to the line orientation of the text. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 31 Glossary cross-stream shift A type of positional shift that applies equally to all glyphs in a style run by raising or lowering the entire style run (or shifts it sideways if it’s vertical text). Compare with-stream shift. current context The rendering context to which OpenGL routes commands issued by your application. current graphics state The parameter values that determine how Quartz renders results as it paints. cryptographic hash function An algorithm that takes any amount of data and transforms it into a fixed-size output value. For a cryptographic hash function to be useful for security, it has to be extremely difficult or impossible to reconstruct the original data from the hash value, and it must be extremely unlikely that the same output value could result from any other input data. See also message digest. current matrix A matrix used by OpenGL to transform coordinates in one system to those of another system, such as the modelview matrix, the perspective matrix, and the texture matrix. GL shading language allows user-defined matrices. current point The last location Quartz used when painting a path. cryptographic hashing The process whereby data is transformed using a cryptographic hash function. current printer The printer displayed in the Printer pop-up menu when the user opens the Print dialog. CSR Certificate signing request. A file that contains personal information used to generate a development certificate. Certificate signing requests are created by the Keychain Access application. current script The AppleScript script currently being executed. current target In AppleScript, the object that is the current default target for commands. CSSM Common Security Services Manager. A public application programming interface for CDSA. CSSM also defines an interface for plug-ins that implement security services for a particular operating system and hardware environment. current transformation matrix An affine transform that Quartz uses to map points from one coordinate space to another. current version One of two numbers used to track minor version information in a framework. It tracks individual builds of your framework and is mostly for internal use by your team. Compare compatibility version. cubic curve A curve defined by a cubic equation. See also Bï¿½zier curve. culling In OpenGL, eliminating parts of a scene that can’t be seen by the observer. cursor The onscreen representation of the mouse’s location. The cursor commonly looks like an arrow, but can also assume such shapes as a pencil, a cross, or a paintbrush, depending on the application and the user’s selection. (Also called a pointer .) CUPS Common UNIX Printing System. An open source architecture commonly used by the UNIX community to implement printing. current application The application that is using the AppleScript component to compile and execute scripts (typically, Script Editor). custom guide In Interface Builder, an alignment tool that is placed by the user in order to align objects to an arbitrary location on the design surface. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 32 Glossary custom install A metapackage or distribution package installation that a user performs after modifying the default option selection. Dashboard A user technology for managing HTML-based programs called widgets. Activating the Dashboard via the F12 key displays a layer above the OS X desktop that contains the user’s current set of widgets. custom patch A subclass of QCPlugIn (page 101)that performs custom processing in the Quartz Composer development environment. Dashcode A graphical application used to build and debug Dashboard widgets. CVS Concurrent Version System. A source-code control system that Xcode can use to manage changes in source code over time and across multiple developers. data An AppleScript class used for data that do not belong to any of the other AppleScript classes; see the data class. DAC Digital-to-analog converter. Circuitry that converts digital data to a corresponding analog signal. DACs are characterized by maximum sampling frequency, amplitude resolution in terms of bit depth, monotonicity, distortion characteristics, and noise floor. Compare user focus. database server A data storage and retrieval system. Database servers typically run on a dedicated computer and are accessed by client applications over a network. data browser A control that provides a standardized look for column browsers (such as seen in the column view of a Finder window or in an Open dialog) and scrolling lists (such as seen in the list view of a Finder window). daemon A process that handles periodic service requests or forwards a request to another process for handling. Daemons run continuously, usually in the background, waking only to handle their designated requests. For example, the httpd daemon responds to HTTP requests for web information. data compression Algorithmic reduction of data size to improve storage or transmission efficiency. Data compression can be lossy or lossless. Compression is a special case of encoding. See also lossless compression, lossy compression, perceptual coding. Darwin The core of OS X, Darwin is an open source project that includes the Darwin kernel, the BSD commands and C libraries, and several additional features. The Darwin kernel is synonymous with the OS X kernel. data fork In a Macintosh file, the section that corresponds to a DOS/Windows file. data formatter In Xcode, a string that specifies how variables are displayed in debugger datatips and the variable list in the debugger. dash In a menu, indicates that an attribute applies to only part of the selection. For example, if a highlighted selection contains text with different styles applied to it, a dash appears next to each style name in the menu. data handler In QuickTime, a piece of software that is responsible for reading and writing a media structure’s data. The data handler provides data input and output services to the media structure’s media handler. See also media handler. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 33 Glossary data modeling The process of building a data model to describe the mapping between a relational database schema and an object model. debugger datatip A way of viewing and modifying the contents of variables using a progressive disclosure mechanism. data reference A reference to a QuickTime media structure’s data. debugger strip A small control strip that appears above the content pane and contains controls for several debugging tasks. data run See run, text run. decibel A dimensionless unit for expressing the ratio of two quantities, abbreviated as dB . The decibel difference between two power levels is equal to 10 times the common logarithm of their ratio. The decibel difference between two voltage levels is equal to 20 times the common logarithm of their ratio. Decibel values are typically associated with a standard voltage or power level. For example, acoustic levels are commonly referenced to 0 dB SPL, equivalent to 20 µPa (micropascals). See also SPL. data source object An object supplied by AppleScript Studio that supplies data to a table view or other view with rows and columns. data-source adaptor In WebObjects, a mechanism that connects your application to a particular database server. For each type of server you use, you need a separate adaptor. WebObjects provides an adaptor for databases conforming to JDBC. date In AppleScript, a class that specifies a time, day of the month, month, and year. declaration In AppleScript, the first occurrence of a variable or property identifier in a script. The form and location of the declaration determine how AppleScript treats the identifier in that script—for example, as a property, global variable, or local variable. date picker A control that allows a user to input date and time information in either a textual or graphical format. dB See decibel. dBu An absolute measure of RMS voltage level in decibels relative to 0.775 Volts RMS. dBu measurements assume a circuit load with infinite impedance. See also RMS. decode In audio, to retrieve the original signal from an encoded representation of it. For lossy encoding schemes such as MP3, the retrieved signal approximates the original signal. See also codec (coder/decoder), encoding. debug rendering mode A view that displays an animation of the data flow in a composition that can help track down issues. In this mode, patches in the workspace change colors as they move from one state to another. A drawer below the view displays log messages. decryption The transformation of ciphertext back into the original plaintext. Compare encryption. See also asymmetric keys, symmetric keys. dedicated network build In Xcode, a distributed build that is effective on large projects using ten or more build servers. See also distributed build. Compare shared workgroup build. debugger A process that lets you pause a program and examine its state. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 34 Glossary deep fetch In WebObjects, an option available to fetch specifications that causes database fetches to occur against the root table and any leaf tables. Applicable to inheritance hierarchies. default output unit An Apple-supplied audio unit that connects with whichever hardware device the user has designated to be the default output. default pager In Mach, one of the built-in pagers. The default pager handles nonpersistent (anonymous) memory. See also anonymous memory, pager, vnode pager. default application The application selected by Launch Services, according to its own implicit binding rules, in which to open a given document or URL in the absence of an explicit binding preference set by the user. default target In AppleScript, the object that receives a command if no object is specified or if the object is incompletely specified in the command. Default (or implicit) targets are specified in tell statements. default build configuration The configuration Xcode uses when a project does not have a definition for the active build configuration. default button The button that provides a safe action in a dialog. The default button is indicated by a pulsing appearance. It is activated when the user presses the Return or Enter key. deferred faults In WebObjects, a special kind of fault that represents a number of other faults in a single object. See also fault, faulting. deferred recognition In the Ink Services technology, the process of recognizing an ink phrase that was drawn by the user at an earlier time. default keyboard access mode The mode in which tabbing and other keystrokes move keyboard focus only between fields that receive keyboard input, such as text entry fields and scrolling lists. See also full keyboard access mode. deinterleaving In digital audio , retrieving discrete channels from an interleaved representation. Also called reverse multiplexing . Compare interleaving. default keychain The keychain accessed by certain Keychain Services functions when no other keychain is specified in the function call. For example, newly created keychain items are stored in the default keychain unless a different keychain is specified in the function call. A default keychain is created for each new login account, but the user can use the Keychain Access utility to designate another keychain as the default. delay The time lag between one audio event and another. In audio processing, the second event is typically a processed or unprocessed copy of the original event. Delay is a settable parameter in the AUDelay audio unit included in OS X. delegation (1) A way of extending a class in an object-oriented framework. In object-oriented design methodology, delegation is a form of class composition. (2) In AppleScript, the use of a continue statement to call a handler in a parent object or the current application. default keychain search list The list of keychains searched by certain Keychain Services functions when no other keychain or list of keychains is specified in the function call. The default keychain search list contains the same keychains as the keychain list displayed in the Keychain Access utility. delivery vehicle The means of transport used by users of a product to obtain the product’s files. These include optical media and the Internet. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 35 Glossary demand paging An operating-system facility that brings pages of data from disk into physical memory only as they are needed. descriptor dispatch source A dispatch source used to process file-related events. A file descriptor source calls your custom event handler either when file data is available for reading or writing or in response to file system changes. deployment build style A methodology of creating a product from a target that makes the product more appropriate for distribution to users. design surface In Interface Builder, the content area of a window object. It’s the area in which you drop views and other visual objects and is also where you manipulate those objects directly. deployment descriptor In WebObjects, an XML file that describes the configuration of a web application. It’s located in the WEB-INF directory of the application’s WAR file and named web.xml . desktop The background on top of which all windows appear; the working environment displayed on Mac computers. deployment tool An HTML-based application through which J2EE application or component archives can be configured or assembled in preparation for deployment in OS X Server. destination printer The printer to which a print job is sent. This is the printer displayed in the Printer pop-up menu when the user clicks Print in the Print dialog. depth In OpenGL, refers to the z coordinate and specifies how far a pixel lies from the observer. destination rectangle The rectangle defining the area in which text is drawn. depth buffer In OpenGL, block of memory used to store a depth value for each pixel. The depth buffer is used to determine whether or not a pixel can be seen by the observer. Those that are hidden are typically removed. destination region The part of a document that can accept data dragged to it. In a document window, the destination region is usually the content area minus the title bar and areas used for controls such as scroll bars and rulers. derived attribute An attribute in a data model that does not directly correspond to a column in a database. Derived attributes are usually calculated from a SQL expression. detail view In Xcode, a view that displays the item or items that you select in the Groups & Files list, providing a convenient way for you to find and access project contents. descent line An imaginary horizontal line that usually corresponds to the bottoms of the descenders in a font. The descent line is the same distance from the baseline for all glyphs in the font, whether or not they have descenders. development build style A methodology of creating a product from a target that makes the product more appropriate for debugging and testing. descriptor An abstract identifier used to access a file, socket, or other system resource. development certificate A file that identifies an iPhone application developer. Xcode uses development certificates to sign application binaries. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 36 Glossary device (1) Computer hardware, typically excluding the CPU and system memory, that can be controlled and can send and receive data. Examples of devices include displays, disk drives, buses, and keyboards. (2) In audio generally, a piece of equipment or a software entity that produces, transforms, transmits, receives, or stores audio data. In MIDI, a piece of equipment or a software entity that responds to MIDI control or provides MIDI data. In Audio Queue Services, a source or destination for audio, such as a microphone or a loudspeaker. device. The program can obtain the device name (which is not persistent across reboots or device removal) from the I/O Kit. device interface In the I/O Kit, a mechanism that uses a plug-in architecture to allow a program in user space to communicate with a nub in the kernel that is appropriate to the type of device the program wishes to control. Through the nub the program gains access to I/O Kit services and to the device itself. From the perspective of the kernel, the device interface appears as a driver object called a user client. device advance The number of pixels of the advance for the glyph as actually drawn on the screen. device matching In the I/O Kit, a process by which an application finds an appropriate device interface to load. The application calls a special I/O Kit function that uses a matching dictionary to search the I/O Registry. The function returns one or more matching driver objects that the application can then use to load an appropriate device interface. Also referred to as device discovery . device color space A color space that is tied to the system of color representation for a particular device. This type of color space is not suitable for interchanges of color data between different devices. device delta A value used to adjust truncated factional values for cases in which fractional positioning can’t be used. Device delta values are usually used when anti-aliasing is turned off. However, these values can be used when anti-aliasing is on, to assure that the glyphs in a connected script (such as one that uses the Zapfino font) are connected smoothly. device space The coordinate system that defines the position and scale (pixel size) of a specific view device. device-independent color space A color representation that is portable between devices and that is used for the interchanges of color data from the native color space of one device to the native color space of another device. Colors in a device-independent color space appear the same when displayed on different devices, to the extent that the capabilities of the device allow. device driver A component of an operating system that deals with getting data to and from a device, as well as the control of that device. A driver written with the I/O Kit is an object that implements the appropriate I/O Kit abstractions for controlling hardware. diacritical marks A mark, such as an accent, that is used in conjunction with a character to indicate phonetic value. device file In BSD, a device file is a special file located in/devthat represents a block or character device such as a terminal, disk drive, or printer. If a program knows the name of a device file, it can use POSIX functions to access and control the associated dialect A version of the AppleScript language that resembles a specific human language or programming language. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 37 Glossary dialog A window designed to elicit a response from the user. See also alert. dilation An effect that takes each bright pixel in the source image and expands it into the shape of the kernel, flipped horizontally and vertically. The contribution of the source pixel to the kernel-shaped region depends on two things: the brightness of the source pixel (brighter pixels contribute more) and the values of the kernel pixels (pixels that are dark, relative to the center of the kernel, contribute more to their locations in the kernel-shaped region than pixels that are bright). diamond In a Window menu, a mark that indicates that a document has been minimized into the Dock. dictionary In AppleScript, the set of commands, objects, and other terminology that is understood by an application or other scriptable entity. You can display an application’s dictionary with Script Editor. dictionary browser Seeterminology browser. dimmed Used to describe text or icons that are grayed out to indicate that they are currently unavailable. Menu items, for example, are dimmed rather than omitted when they aren’t applicable at a particular moment. Diffie-Hellman key exchange A protocol that provides a way for two ends of a communication session to generate symmetric private keys through the exchange of public keys. digest See message digest. diphthong A complex vowel sound that can be phonetically represented by 2 characters. The characters represent the initial and final sounds of the diphthong. digital certificate A collection of data used to verify the identity of the holder or sender of the certificate. A digital certificate must conform to some standard in order for the recipient to be able to interpret it. OS X and iOS support the X.509 standard for digital certificates. See also certificate chain. direct parameter In AppleScript, the parameter immediately following a command, which typically specifies the object to which the command is sent. digital ID See digital certificate. Direct to Java Client A WebObjects development approach that can generate a Java Client application from a model. digital rights management See DRM. digital signal processing See DSP. Direct to Java Client Assistant A WebObjects tool used to customize a Direct to Java Client application. digital signature A way to ensure the integrity of a message or other data using public key cryptography. To create a digital signature, the signer generates a message digest of the data and then uses a private key to encrypt the digest. The signature includes the encrypted digest and identifies the signer. Anyone wanting to verify the signature uses the signer’s digital certificate, which contains the public key needed to decrypt the digest and specifies the algorithm used to create the digest. Direct to Web A WebObjects development approach that can generate a web application from a model. Direct to Web Services A WebObjects development approach that can generate a web service application from a model. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 38 Glossary Direct to Web template In WebObjects, a component used in Direct to Web applications that can generate a webpage for a particular task (for example, a list page) for any entity. discontinuous highlighting Highlighting that exactly matches the selection range it corresponds to. It may consist of discontinuous areas when the selection range crosses direction boundaries. Compare contiguous highlighting. direct-access functions ATSUI functions that allow you to manipulate glyph data directly. discontinuous selection A selection in which unselected objects are between selected objects. direction boundary A point, between offsets in memory or glyphs in a display, at which the direction of stored or displayed text changes. disk image A file-based enclosure that facilitates the transport of a directory structure on the Internet. Disk images can also be compressed to allow a product’s files to be placed on optical media. direction run A contiguous (in memory) sequence of characters having the same right-to-left or left-to-right line direction. dispatch queue A Grand Central Dispatch (GCD) structure that you use to execute your application’s tasks. GCD defines dispatch queues for executing tasks either serially or concurrently. directory A file-system object containing zero or more other named objects (files or other directories). disc menu In DVD Player, the main menu from which titles are selected. The disc menu is sometimes called the title menu, which more accurately refers to the menu within a title from which chapters and other features can be selected. dispatch source A Grand Central Dispatch (GCD) data structure that you create to process system-related events. display coordinate system The QuickDraw graphics world, which can be used to display QuickTime movies, as opposed to the movie’s time coordinate system, which defines the basic time unit for each of the movie’s tracks. Compare time coordinate system. disclosure button A control that expands a dialog to provide the user with additional choices that are associated with a specific list-based selection control (such as a pop-up menu). disclosure triangle A control that allows the display, or disclosure, of information that elaborates on the primary information in a window. Disclosure triangles are used in the Finder’s list view; clicking a triangle displays a folder’s contents. display link A high-priority thread that, based on a specified hardware display, makes intelligent guesses as to how often frames must be output to synchronize with the display’s refresh rate. discontinuity In an audio data stream, a distinct break in the sequence of transmitted data. A discontinuity entails a period in which the stream is undefined. See also TCP stream. display list A list of OpenGL commands that have an associated name and that are uploaded to the GPU, preprocessed, and then executed at a later time. Display lists are often used for computing-intensive commands. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 39 Glossary display name The name of a file as it appears to the user. The display name reflects the user’s preference for hiding or showing the filename extension. provide a streamlined packaging experience for developers and an enhanced installation experience for users. See also distribution script, metapackage. distribution script An XML file with the extension .dist that contains all the information that defines an installation experience in a distribution package. See also distribution package. display order The order in which glyphs are drawn on a screen. Glyphs are always drawn in left-to-right order. Because not all text is read left-to-right, the display order of glyphs may be different from the storage order of their corresponding character codes in memory. dither In audio, a low-amplitude noise applied to a signal to reduce quantization error. See also quantization noise. Display pop-up menu In Xcode, a menu that lets you choose when to display the Build Results window, overriding the default settings in the Building pane of Xcode Preferences. dithering A technique used to improve picture quality when you are attempting to display an image that exists at a higher bit-depth representation on a lower bit-depth device. For example, you might want to dither a 24-bits-per-pixel image for display on an 8-bit screen. display text The visual representation of the text of a text layout object. Display text consists of a sequence of glyphs, arranged in display order. Compare source text. DLIL Data Link Interface Layer. The part of the OS X kernel’s networking infrastructure that provides the interface between protocol handling and network device drivers in the I/O Kit. A generalization of the BSD “ifnet” architecture. distance In surround sound and immersive audio, the real or apparent straight line distance of an audio source from the listener. distortion A difference, typically unintentional and undesired, between the signals on the input and output of an audio device. Commonly measured types of distortion include harmonic distortion, intermodulation distortion, quantization distortion, and jitter. Intentional differences between input and output signals, such as level or equalization differences, are not described as distortion. Compare noise. DMA Direct memory access. A capability of some bus architectures that enables a bus controller to transfer data directly between a device (such as a disk drive) and a device with physically addressable memory, such as that on a computer’s motherboard. The microprocessor is freed from involvement with the data transfer, thus speeding up overall computer operation. See also bus master. .dmg file An OS X disk image file. distributed build In Xcode, a build that uses several computers to compile source files. Dock A user-configurable, onscreen, interface element that provides a simple way for users to launch frequently used applications and documents. It also houses minimized windows and the Trash. distribution package A metapackage that contains a distribution script that specifies the installation experience for a product. Distribution packages 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 40 Glossary document A unit or collection of data, contained in a file or sandboxing, that can be operated on by an application. In Search Kit, anything that contains text and that the Search Kit client application addresses as a document—an RTF document, a PDF file, a Mail message, an Address Book entry, the contents at an Internet URL, the result of a database query, and so on. See also document URL object. client application. Search Kit document URL objects may be converted to or from CFURL objects. See also document, parent document URL object, virtual address. document window A window containing file-based data that users create and store. documentation feed An RSS-style web feed that Xcode can check periodically to determine when a publisher makes available updates to a documentation set or releases a new documentation set. document collection See corpus. document file A file containing a document. document-modal A window state where the user cannot do anything else within a particular document until the window is dismissed. Sheets are document-modal windows. Compare application-modal, system modal. documentation node In Xcode documentation sets, a documentation file or a folder of files within a set. Each documentation node is associated with a location that identifies the file to display when a user selects that node in the documentation window. A node may be a single document, a collection of documents, or a single HTML documentation page. document-modal dialog A dialog that prevents the user from performing further operations in the document until the user dismisses the dialog. All sheets are document modal and all Aqua document-modal dialogs should be sheets. See also application-modal dialog, sheet. documentation search In Xcode, a search composed of a search term, search type, and search scope. document object hierarchy A collection of documents in which each document exists at a location relative to a root document. The locations may may be real, as in a file system, or virtual. documentation set A subset of the reference library packaged as a standard OS X bundle. Each documentation set contains HTML-based content as well as indexes into that content, which Xcode uses to perform quick documentation searches. Also called a doc set . document package A package containing a document along with related resources. Documentation window In Xcode, a window designed for browsing and searching developer documentation. It provides access to a wider and more detailed view of the documentation than the Research Assistant. document type A family of document files characterized by a given file type, creator signature, or filename extension. Compare URL type. document type definition See DTD. domain (1) In a file system, an area reserved for software, documents, and resources and limiting the accessibility of those items. A domain is segregated document URL object A URL to a document. In Search Kit, a document URL object comprises a scheme, a parent document URL object, and a name, with the format of each component defined by the 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 41 Glossary from other domains. There are four domains: user, local, network, and system. (2) In networking, a complete protocol family. drawer A child window that slides out from a parent window and that the user can open or close (show or hide) while the parent window is open. Drawers contain controls that are fairly frequently accessed but don’t need to be visible at all times. double angle brackets Characters («,») typically used by AppleScript to enclose raw data. With a U.S. keyboard, you can enter double angle brackets (also known as chevrons) by typing Option-Backslash and Shift-Option-Backslash. driver See device driver. driver layer I/O Kit drivers for various networking types. double buffering The practice of using a front and back color buffer to achieve smooth animation. The back buffer is not displayed, but swapped with the front buffer. driver matching In the I/O Kit, a process in which a nub, after discovering a specific hardware device, searches for the driver or drivers most suited to drive that device. Matching requires that a driver have one or more personalities that specify whether it is a candidate for a particular device. Driver matching is a subtractive process involving three phases: class matching, passive matching, and active matching. See also personality. downgradable component A product component, such as an application binary or a plug-in, that can be replaced with an earlier version in an installation process. DPCM Differential pulse-code modulation. A variant of pulse-code modulation that encodes the difference between the current and previous sample. driver personality A dictionary of key/value pairs that specify device property values, such as family type, vendor name, or product name. A driver is suitable for any device whose properties match one of the driver’s personalities. dpi Dots per inch in the x and y directions; used to measure the resolution of a screen or printer. The higher the value, the finer the detail of the image. driver stack In an I/O connection, the series of driver objects (drivers and nubs) in client/provider relationships with each other. A driver stack often refers to the entire collection of software between a device and its client application (or applications). drag and drop The technique of dragging an item, such as a graphic or selected text, and dropping it on a suitable destination, such as another document. drag area The portion of a window that users can use to move the window. DRM Digital rights management. A generic term referring to embedded, electronic restriction over the use of electronic content. Usually applied to copyrighted material. See also FairPlay. drawable object In OS X, an object allocated outside of OpenGL that can serve as an OpenGL framebuffer. A drawable object can be any of the following: a window, a view, a pixel buffer, offscreen memory, or a full-screen graphics device. See also framebuffer object. drop capital A large uppercase letter that drops below the main line of text for aesthetic reasons. dropframe In video, a synchronizing technique that skips timecodes to keep them current with video frames. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 42 Glossary droplet A script application that launches when you drag a file or folder icon in the Finder and drop it on the droplet’s icon. A droplet receives a list of descriptors for the folders or files dropped on it and typically performs operations on each item in the list. DVD An optical storage medium that provides greater capacity and bandwidth than CD-ROM; DVDs are frequently used for multimedia as well as data storage. DVD event A notification of a state change in DVD Playback Services during playback. An event is specified with a type identifier and associated data. Client applications can register callback functions to receive events of interest. DSP Digital signal processing. In audio, analyzing or transforming digital representations of audio. Such transformations include, among others, filtering and equalization, reverberation, level compression, data compression, and sound effects such as pitch shifting. Digital signal processing can be performed by hardware, software, or a combination of both. DVD player (1) A hardware product that decodes and plays DVD-Video media stored on an optical disc. The output device is generally a television set, although some players have built-in displays and speakers. (2) A computer software program that decodes and plays DVD-Video media stored on an optical disc or a mass storage device such as a hard drive. dSYM file A file that stores an executable’s debugging information to minimize the size of the executable file without compromising the program’s debugging experience. DTD Document type definition. A file that describes the structure of an XML document. DVD-Video A standard for storing and reproducing audio and video on DVD-ROM discs, based on MPEG-2 video compression, Dolby Digital and MPEG audio, and other proprietary data formats. dual caret A type of caret that, at the boundary between text of opposite directions, divides into two parts: a high caret and a low caret, each measuring half the line’s height. The two separate half-carets merge into one in unidirectional text. dyld Dynamic link editor. The library manager for code in the Mach-O executable format. The dynamic link editor is a dynamic library that “lives” in all Mach-O programs on the system. See also CFM, Mach-O. Duplex pane A pane in the Print dialog (available for some printers) that provides the option to print to both sides of a sheet of paper. dyld (dynamic link editor) A utility that allows programs to dynamically load (and link to) needed functions. duration (1) The length of time, in seconds, it takes for an animation to complete. (2) In QuickTime, time values that are interpreted as spans of time, rather than as points in time. dynamic element A dynamic version of an HTML element. WebObjects includes a list of dynamic elements with which you can build web components. [email protected] An Apple technology you can use to add interactivity to a DVD when played on a computer. [email protected] makes it possible to open a web browser to display HTML files, or open a program to view PDF, PICT, or JPEG files. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 43 Glossary dynamic guide In Interface Builder, an alignment tool that provides information about the position of a view relative to other objects on the design surface. Dynamic guides appear only when the Option key is held down. symbols at runtime, but attempts to do so only when those symbols are referenced during program execution. easy install A metapackage or distribution package installation that a user performs using the default option selection. dynamic library A library for which binding of undefined symbols is delayed until execution. Code in dynamic shared libraries can be shared by multiple, concurrently running programs. See also dynamic shared library. EBU European Broadcasting Union. A Europe-based, international, audio and broadcasting standards organization. edge offset A byte offset into the source text associated with a text layout object that specifies a position between byte values. Edge offsets in source text are related to caret positions in display text. Compare byte offset. dynamic link editor See dyld. dynamic linking The binding of modules, as a program executes, by the dynamic link editor (dyld). Usually the dynamic link editor binds modules into a program lazily (that is, as they are used). Thus modules not actually used during execution are never bound into the program. editing context An object that stores and manages a group of enterprise-object instances. An editing context, which is an instance of the EOEditingContext class, provides an in-memory view of data in a data store. Changes made to enterprise-object instances in an editing context are pushed to the data store by invoking a specific method. In addition, those changes can be undone, even after they have been committed to the corresponding data store. dynamic menu item A menu item that changes when the user presses a modifier key. For example, in the Finder File menu, if the user presses the Option key, the Close Window command changes to Close All. See also toggled menu item. dynamic range A quality measure for an audio device or system that describes the difference between the loudest and softest signal that can appear at the output of the device. Dynamic range is equal to the ratio of dynamic ceiling to noise floor, typically described in decibels. See also ceiling, decibel, noise floor. edit list In QuickTime, a data structure that arranges a media structure into a time sequence. Edit menu A menu that provides commands for changing (editing) the contents of documents. It contains commands such as Cut, Copy, and Paste. dynamic shared library A library whose code can be shared by multiple, concurrently running programs. Programs share exactly one physical copy of the library code and do not require their own copies of that code. With dynamic shared libraries, a program not only attempts to resolve all undefined edit state In QuickTime, information defining the current state of a movie or track with respect to an edit session. QuickTime uses edit states to support undo facilities. effect description A data structure that specifies which component to use to implement an effect in a movie and how the component is configured. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 44 Glossary effect track In QuickTime, a modifier track that applies an effect (such as a wipe or dissolve) to a movie. See also modifier track. embedded speech command A command embedded in textual input that a speech synthesizer interprets and applies to the pronunciation of the spoken version. effect unit In Core Audio, an audio unit of type'aufx' that employs DSP to modify a stream of digital audio. See also DSP. EMMI External Memory Management Interface. Mach’s interface to memory objects that allows their contents to be contributed by user-mode tasks. See also external pager. EGID Effective Group ID. See GID. EJB (Enterprise JavaBeans) Enterprise JavaBeans. A specification that provides an infrastructure through which data-based components can be developed and deployed in a variety of platforms. emphasized mini system font The bold version of the mini system font. emphasized small system font The bold version of the small system font. element (1) In an XML file, such as a scripting definition file, a tag-delimited unit of data. (2) In Core Audio, an audio unit programming context nested within a scope. When part of an input or output scope of an audio unit, an element is analogous to a device signal bus—and is sometimes called a bus . See also audio unit, scope. (3) In a scripting definition file (or an AppleScript dictionary viewer), a characteristic of an object that refers to a contained collection of related objects. Synonymous with a key-value coding to-many relationship. A document object might have a graphics element (or to-many relationship). emphasized system font The bold version of the system font. empty list In AppleScript, a list containing no items. enabled control A control state where the control appears normally (that is, not grayed out) and responds to user input when active. Encapsulate transformation In Xcode, a refactoring operation that creates accessors for the transformation item, reduces its visibility, and changes code that directly accesses the item to use the accessors instead. elevation In surround sound and immersive audio, the real or apparent vertical angle of an audio source referenced to a line drawn from a listener’s head to a point directly ahead of the listener. encoding In audio, the algorithmic conversion of a signal from one representation to another. For example, compressing linear PCM data to AAC format is a form of encoding. Can be applied to perceptual or lossless data compression. See also codec (coder/decoder), decode. Compare data compression. ellipsis character Three unspaced periods that appear in menus, buttons, and other controls to indicate that additional information will be required to complete the command. Generate an ellipsis with Option-semicolon. encrypt To secure data so that it cannot be read by unauthorized entities, in such a way that its original state can be restored later (decrypted). In most embedded objects Graphics, sound, or movie data that is in a text object along with text data. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 45 Glossary cryptographic systems, encryption and decryption are performed by manipulating the data with a string of bytes called a key . equalization In image manipulation, a histogram operation that makes the resultant image conform to a uniform histogram, ensuring an equal frequency of pixel intensities. encryption The transformation of data into a form in which it cannot be made sense of without the use of some key. Such transformed data is referred to as ciphertext . Use of a key to reverse this process and return the data to its original (or plaintext ) form is called decryption . erosion In image manipulation, a morphological operation that is similar to dilation. It takes dark pixels in an image and spreads them around, causing them to “eat away” (or erode) objects in an image. error expression In AppleScript, an expression, usually a text object, that describes an error. endpoint See MIDI endpoint. enterprise object In WebObjects, an object that conforms to the key-value coding protocol and whose properties can map to stored data. An enterprise object brings together stored data with methods for operating on that data. error handler In AppleScript, a collection of statements that are executed in response to an error message. Error Handling pane A pane in the Print dialog that lets the user specify the actions to take when certain errors occur. Enterprise Objects Enterprise Objects is a set of frameworks for building feature-rich database applications that encapsulate business logic, yet are independent of any particular data source. error message A message that is supplied when an error occurs during the handling of a command. error number An integer that identifies an error. entitlement A property that allows an application to access a protected iOS feature or capability. Ethernet A family of high-speed local area network technologies at the physical layer of the OSI model. entity In Entity-Relationship modeling, a distinguishable object about which data is kept. An entity typically corresponds to a table in a relational database; an entity’s attributes, in turn, correspond to a table’s columns. An entity is used to map a relational database table to a Java class. See also attribute, table. EUID Effective User ID. See UID. evaluation The conversion of an expression to a value. even-odd rule A fill rule that determines when to paint a pixel. The outcome does not depend on the direction that path segments are drawn. Compare nonzero winding number rule. Entity-Relationship modeling A discipline for examining and representing the components and interrelationships in a database system. Also known as ER modeling, this discipline factors a database system into entities, attributes, and relationships. See also object-relational mapping. event (1) A constant that notifies an application that some action is occurring, or has occurred. (2) In AppleScript an action an object can respond to. For example, a button click is an event that may result in execution of a clicked handler for the button that was clicked. Compare SMB/CIFS. (3) In Interface EOModeler A tool used to create and edit models. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 46 Glossary Builder, a type of connection that is specific to iOS applications. Events represent different phases of user interaction for a control. Each event connection can also have multiple assigned target objects, each with its own distinct action message. event timer A timer mechanism that fires once, or at periodic intervals, calling a callback procedure when doing so. event track In audio, a stream of MIDI or event data which can be played using a music player. See also channel, sequence. event class The general category an event belongs to, typically associated with an particular action or user-interface element. Example classes are window events and volume events. Compare event kind. event type The combination of event class and event kind that uniquely identifies an event to the Carbon Event Manager. See also event class, event kind. event coalescing See mouse event coalescing. event handler A callback procedure or function that processes one or more events. every reference form In AppleScript, a reference form that specifies every object of a particular type in a container. event kind A specific type of event within an event class (for example, a mouse-down event). Compare event class. exception An interruption to the normal flow of program control that occurs when an error or other special condition is detected during execution. An exception transfers control from the code generating the exception to another piece of code, generally a routine called an exception handler. event loop In the Carbon Event Manager, an execution loop that obtains events from the Window Server and places them in an event queue. The event loop also fires timers. exception port A Mach port on which a task or thread receives messages when exceptions occur. event queue A first-in-first-out stack where events pertaining to a thread are stored. Each preemptively scheduled thread has its own event queue. exclusive feature type A feature for which you can choose only one of the available feature selectors, such as whether numbers are to be proportional or fixed-width. Compare nonexclusive feature type. event source An I/O object that corresponds to a type of event that a device driver can be expected to handle; there are currently event sources for hardware interrupts, timer events, and I/O commands. The I/O Kit defines a class for each of these event types, respectively IOInterruptEventSource, IOTimerEventSource, and IOCommandGate. executable An application that uses a project’s product and can be launched in order to debug that product. executable environment Defines how Xcode should execute a product in response to the Go command. event target An object to which an event is sent. An event target is typically a user-interface element, such as a control or a window. execute condition In Xcode, a state that triggers a breakpoint. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 47 Glossary exit statement In AppleScript, a statement used in the body of a repeat statement to exit that statement. Extract transformation In Xcode, a refactoring operation that creates a function or method with the selected code as its body. explicit run handler In AppleScript, a handler at the top level of a script object that begins with on run and ends with end . A single script object can include an explicit run handler or an implicit run handler, but not both. eye coordinates In OpenGL, the coordinate system with the observer at the origin. Eye coordinates are produced by the modelview matrix and passed to the projection matrix. factored application An application that uses a helper tool to perform specific tasks. Interprocess communication mechanisms are used to communicate between processes. In a factored application that uses Authorization Services, the code that performs privileged operations is factored into a separate helper tool. expression In AppleScript, any series of words that has a value. extension (1) An object module that can be dynamically added to a running system; often used as a synonym for kernel extension. (2) A feature of OpenGL that’s not part of the OpenGL core API and therefore not guaranteed to be supported by every implementation of OpenGL. The naming conventions used for extensions indicate how widely accepted the extension is. The name of an extension supported only by a specific company includes an abbreviation of the company name. If more then one company adopts the extension, the extension name is changed to include EXT instead of a company abbreviation. If the OpenGL Architecture Review Board approves an extension, the extension name changes to include ARB instead of EXT or a company abbreviation. factory A function in a printing plug-in that returns a pointer to an instance of the requested interface. FairPlay The DRM (digital rights management) system built into Apple’s QuickTime technology and used by the iPod music player, the iTunes music application, and the iTunes store. These systems use FairPlay to encrypt some AAC files to restrict their playback to authorized devices. family In the I/O Kit, a collection of software abstractions that are common to all devices of a particular category. Families provide functionality and services to drivers. Examples of families include protocol families (such as SCSI, USB, and Firewire), storage families (disk drives), network families, and families that describe human interface devices (mouse and keyboard). externally framed Describes a variable bit rate audio format where information about the sizes of the frames is transmitted separately from the audio data stream. Compare internally framed. See also webpage template. fan out In electronics generally, to direct one output signal to multiple inputs. Audio units cannot perform fan out of this sort. To feed multiple audio unit inputs, you direct an audio unit output to a buffer (such as a splitter unit) that has multiple outputs, each of which can connect to a separate audio unit input. external pager A module that manages the relationship between virtual memory and a backing store. External pagers are clients of Mach’s EMMI. The pager API is currently not exported to user space. The built-in pagers in OS X are the default pager, the device pager, and the vnode pager. See also EMMI. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 48 Glossary fast user switching A feature that allows users on a multiple-user computer to access their desktop, documents, and applications without requiring other logged in users to quit their applications. feature type A group of font features in a style object that are applied to each style run based on font defaults. See also feature selectors. fence A token used by the GL_APPLE_fence extension to determine whether a given command has completed or not. FAT File allocation table. A data structure used in the MS-DOS file system. Also synonymous with the file system that uses it. The FAT file system is also used as part of Microsoft Windows and has been adopted for use inside devices such as digital cameras. fetch In Enterprise Objects applications, to retrieve data from the database server into the client application, usually into enterprise objects. fetch specification In Enterprise Objects applications, used to retrieve data from the database server into the client application, usually into enterprise objects. fat files See universal binaries. fault (1) In the virtual-memory system, faults are the mechanism for initiating page-in activity. They are interrupts that occur when code tries to access data at a virtual address that is not mapped to physical memory. Soft faults happen when the referenced page is resident in physical memory but is unmapped. Hard (or page) faults occur when the page has been swapped out to backing store. See also page, virtual memory. (2) A type of object in Enterprise Objects that represents a partially formed enterprise object instance. Faults are proxy or stand-in objects that provide performance benefits by delaying the retrieval of data in an enterprise object until it’s absolutely needed. fetch timestamp An attribute of an EOEditingContext object that records the time of the most recent fetch of objects into that editing context. FIFO First-in first-out. A data processing scheme in which data is read in the order in which it was written, processes are run in the order in which they were scheduled, and so forth. file descriptor A per-process unique, nonnegative integer used to identify an open file (or socket). file fork A section of a Macintosh file. See also data fork, resource fork. faulting A mechanism used by WebObjects to increase performance whereby destination objects of relationships are not fetched until they are explicitly accessed. file GID The GID associated with a file-system object. Each file-system object has a user ID (the file UID, commonly referred to as the file’s owner), a group ID (the file GID, commonly referred to as the file’s group), and three sets of permission bits, known as owner, group, and other permissions. The first set of bits controls access to the object by the owner, the second controls access by members of the group, and the third controls access by everyone else. See also process GID. favorites bar In the Xcode project window, an area below the toolbar that lets you save frequently accessed items and return to them quickly. feature selectors A means of defining particular font features in a feature type. See also feature type. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 49 Glossary File History menu In Xcode, a pop-up menu in the navigation bar that contains all the files that you have viewed in the text editor, with the current file at the top of the list. systems specify conventions for naming files, storing data in files, and specifying locations of files. See also volume format. file-system reference A data object of type FSRef designating a file residing on a local or remote file-system volume. File Info window In Xcode, the Info window for inspecting and editing settings for file, framework, and folder references. file type A four-character code associated with a file that characterizes its nature or the structure of its contents. File menu A menu that contains commands that provide housekeeping tasks for files, such as Save As. file type atom An atom of type 'ftyp', which defines which file specifications a file is compatible with. filename extension A string of characters at the end of a filename, preceded by a period ( . ), that characterizes the nature of the file or the structure of its contents. File Types preferences pane An Xcode preferences pane that lists all the folder and file types that Xcode handles and the preferred editor for each of those types. file package A directory that the Finder presents to users as if it were a file. In other words, the Finder hides the contents of the directory from users. This opacity discourages users from inadvertently (or intentionally) altering the contents of the directory. See also bundle. file UID The UID of a file system object, used to determine the object’s permissions. Each file system object has a user ID (the file UID, commonly referred to as the file’s owner), a group ID (the file GID, commonly referred to as the file’s group), and three sets of permission bits, known as owner, group, and other permissions. The first set of bits controls access to the object by the owner (any process whose effective UID is equal to the file UID); the second controls access by members of the group; and the third controls access by everyone else. file preview In QuickTime Player, a thumbnail picture from a movie that is displayed in the Open File dialog box. See also thumbnail picture. file’s group See file GID. file’s owner See file UID. File’s Owner In Interface Builder, the runtime object that manages the contents of a nib file. The File’s Owner is typically a controller object that maintains pointers to key objects in a nib file and responds to user interactions with those objects. fill A drawing operation that paints the area within a path. filling A drawing operation that paints an area contained within a path, using either a solid color or a pattern. Quartz has two rules that it can use to determine whether a point should be filled—the winding number rule and the even-odd rule. file system A part of the kernel environment that manages the reading and writing of data on mounted storage devices of a certain volume format. A file system can also refer to the logical organization of files used for storing and retrieving them. File 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 50 Glossary filter (1) In Image Kit, code that uses Core Image to process digital images. (2) In vImage, an image process that when applied to an image causes its appearance to change. Many filters use kernel convolution to achieve their effect. Emboss, blur, smooth, and edge detect are all examples of common image filters that use convolution kernels. (3) In AppleScript, a phrase, added to a reference to a system or application object, that specifies elements in a container that match one or more conditions. first responder In object-oriented programming, the object given the first opportunity to respond to events. The first responder object is determined dynamically at runtime based on several conditions, including which view is selected or has focus and which view is willing to accept certain types of events. If the first responder does not handle an event, it passes the event to other objects in the responder chain. fixed point A point that uses fixed-point numbers to represent its coordinates. QuickTime uses fixed points to provide greater display precision for graphical and image data. filter browser The user term for the Image Kit filter browser panel class (IKFilterBrowserPanel), which allows users to browse Core Image filters. fixed-point model A model for extending a continuous selection using Shift-click, in which the user can extend the selection on either side of the insertion point. Compare addition model. filtering A process that modifies an image by combining pixels or texels. filter reference form In AppleScript, a reference form that specifies all objects in a container that match a condition specified by a Boolean expression. fixed-point sample A digital audio simple message that uses a fixed-point numerical representation, such as 8.24. Fixed-point samples support fixed-point arithmetic, which is a less computation-intensive alternative to floating-point arithmetic. finalization action An action required after a completed installation process. The possible finalization actions are log-out, restart, and shutdown. fixed-priority policy In Mach, a scheduling policy in which threads execute for a certain quantum of time, and then are put at the end of the queue of threads of equal priority. Finder The system application that acts as the primary user interface for file-system interaction. firewall Software (or a computer running such software) that prevents unauthorized access to a network by users outside the network. (A physical firewall prevents the spread of fire between two physical locations; the software analog prevents the unauthorized spread of data.) fixed rectangle A rectangle that uses fixed points to represent its vertices. QuickTime uses fixed rectangles to provide greater display precision. Flash A vector-based graphics and animation technology. Flash data is exported by SWF files. flattened attribute In WebObjects, an attribute that is added from one entity to another by traversing a relationship. FireWire Apple’s implementation of the IEEE 1394 standard serial bus for connecting digital devices such as cameras and hard drives. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 51 Glossary flattening The process of copying all of the original data referred to by reference in QuickTime tracks into a QuickTime movie file. This can also be called resolving references . Flattening is used to bring in all of the data that may be referred to from multiple files after QuickTime editing is complete. It makes a QuickTime movie stand-alone—that is, it can be played on any system without requiring any additional QuickTime movie files or tracks, even if the original file referenced hundreds of files. The flattening operation is essential if QuickTime movies are to be used with CD-ROM discs. folder A directory presented to the user in such a way that its contents are accessible (subject to the appropriate permissions) for browsing. Compare package. font A collection of glyphs that usually have some element of design consistency such as the shapes of the counters, the design of the stem, the stroke thickness, or the use of serifs. font attributes A group of flags that modify the behavior or identity of a font. font description A table that contains data that fully describes a font. floating input window A window used for text entry by an input method. font family A group of fonts that share certain characteristics and a common family name. floating window A window that is similar to a standard Window Manager window except that is occupies a special layer so that it always remains in front of any application windows. font features The set of typographic and layout characteristics that create a specific appearance for a glyph. flushness See alignment. font ID A value that identifies a font to the font management system. The font ID is assigned to a font at system startup; the specific value does not persist across system startups. focus box In Xcode, a box that code focus uses to delineate scopes. focus center In Xcode, code in the text editor at the lowest scope. Code focus highlights a source file’s scope levels using a grayscale. font instance A setting identified by the font’s designer that matches specific values along the available variation axes and gives those values a name. focus ribbon In Xcode, a vertical strip to the right of the gutter in the text editor. You can use the focus ribbon to change where the focus box is. font name A set of specific information in a font object about a font, such as its family name, style, copyright date, version, and manufacturer. Some font names are used to build menus in an application, whereas other names are used to identify the font uniquely. focus ring Highlighting around the onscreen area that is ready to accept user input. fog In graphics, an effect achieved by fading colors to a background color based on the distance from the observer. Fog provides depth cues to the observer. font run A contiguous (in memory) sequence of characters having the same font. font variation An algorithmic way to produce a range of typestyles along a particular variation axis. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 52 Glossary foreign key In relational databases, an attribute in an entity that gives it access to rows in another entity. This attribute must be the primary key of the related entity. For example, an Employee entity can contain the foreign key deptID , which matches the primary key in the entity Department. You can then use deptID as the source attribute in Employee and as the destination attribute in Department to form a relationship between the entities. See also primary key, relationship. four-character code Four bytes of data that can be expressed as a string of four characters in the Mac OS Roman encoding. In AppleScript, used to uniquely identify terms and other items in an application’s scriptability information. fragment In OpenGL, the color and depth values for a single pixel; a fragment can also include texture coordinate values. A fragment is the result of rasterizing primitives. fragmentation In Search Kit, an unwanted increase in index size due to accumulation of unused capacity. Over time, as documents get added to and removed from an index, the index may become fragmented—its constituent documents and terms may become arranged in a manner that includes a significant amount of unused disk or memory space. See also compact. fork (1) A stream of data that can be opened and accessed individually under a common filename. The Macintosh Standard and Extended file systems store a separate data fork and a resource fork as part of every file; data in each fork can be accessed and manipulated independently of the other. (2) In BSD, fork is a system call that creates a new process. formal parameter See parameter variable. frame (1) In video, a single image in a sequence of images. (2) In text handling, the viewable area of a text object; the view rectangle. Compare destination rectangle. (3) In Core Audio, a set of samples that contains one sample from each channel in an audio data stream. In the most common case, the samples in a frame are time-coincident—that is, sampled at the same moment. For example, in a stereo stream each frame contains one sample from the left channel and a time-coincident sample from the right channel. More generally, the various channels in a stream, and therefore in a frame, may be from unrelated sources and may have originated at unrelated times. See also packet. Format menu An optional menu that contains formatting commands. format standard A television video broadcast format standard. DVD Playback Services supports two format standards: the NTSC format used in North America and Japan, and the PAL format used in Europe and other continents. formatting printer The printer displayed in the “Format for” pop-up menu in the Page Setup dialog. The default formatting printer is the generic Any Printer. The printing system provides default page and paper sizes for this printer. framebuffer (1) In image display, a highly accessible part of video RAM (random-access memory) that continuously updates and refreshes the data sent to the devices that display images onscreen. (2) In OpenGL, the collection of buffers associated with a window or a rendering context. Foundation framework A framework that defines a layer of useful primitive object classes, including support for Unicode strings, allocation and deallocation of objects, arrays and collections, dates, ports, and more. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 53 Glossary framebuffer attachable image In OpenGL, the rendering destination for a framebuffer object. frequency indicates the number of digital samples taken per unit time. Frequency is typically measured in Hertz (cycles per second). framebuffer object An OpenGL extension that allows rendering to a destination other than the usual OpenGL buffers or destinations provided by the windowing system. A framebuffer object (FBO) contains state information for the OpenGL framebuffer and its set of images. A framebuffer object is similar to a drawable object, except that a drawable object is a window-system-specific object whereas a framebuffer object is a window-agnostic object. The context that’s bound to a framebuffer object can be bound to a window-system-provided drawable object for the purpose of displaying the content associated with the framebuffer object. frustum The region of space that is seen by an observer and that is warped by perspective division. FSAA Full scene anti-aliasing. A technique that takes multiple samples at a pixel and combines them with coverage values to arrive at a final fragment. full keyboard access mode The mode in which tabbing and other keystrokes move keyboard focus to more interface elements than is possible in default keyboard access mode. full-text search In Xcode, search option that looks for the documents whose content matches a search term. The search term can be a word or phrase or may be an elaborate expression using Boolean operators and wildcard characters frame rate (1) The rate at which video content is recorded or displayed, in number of frames per second. Frame rates may be fractional. (2) In Core Audio, the number of frames played per second for an audio data stream. Compare sample rate. function key One of the keys with the letter F and a number, plus the Help, Home, Page Up, Page Down, Del, and End keys. framework A type of bundle that packages a dynamic shared library with the resources that the library requires, including header files and reference documentation. Function menu In Xcode, a pop-up menu in the navigation bar that lists the identifiers in the current file. framing See stroke. gain In audio, the ratio of output level to the corresponding input level for a device. Level is typically represented in terms of power or voltage, but gain is unitless and is identical whether voltages or powers were used to calculate it. Because gain is a ratio, it is usually described using decibels. A gain of 0 dB indicates no change in level, while a gain of 10 dB is perceived as approximately a doubling in loudness—depending on the nature of the sound and on the initial loudness. free atom An atom of type 'free', which you can include in a QuickTime file as a placeholder for unused space. FreeBSD A variant of the BSD operating system. frequency The number of times a repeating phenomenon or activity occurs per unit time. The frequency of a sound wave is determined by the number of wavelengths (or fractions thereof ) that pass a particular point per unit time. Sampling gamma correction An operation that changes color intensity values to correct for the nonlinear response of the eye or of a display. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 54 Glossary GCD Grand Central Dispatch, an OS X technology (available in OS X v10.6 and later) for executing asynchronous tasks concurrently. global variable A variable that is available anywhere in the script in which it is defined. GLU The OpenGL Utilities library. gdb GNU debugger. gdb is a powerful, source-level GLUT The OpenGL Utility Toolkit, which is independent of the window system. In OS X, GLUT is implemented on top of Cocoa. debugger with a command-line interface. It’s a popular open source debugger and is included with the OS X developer tools. GLX An OpenGL extension that supports using OpenGL within a window provided by the X Window system. Generic color space A device-independent color space chosen automatically by OS X to produce the best color for the drawing destination. glyph The distinct visual representation of a character in a form that a screen or printer can display. A glyph may represent one character (the lowercase a), more than one character (the fi ligature), part of a character (the dot over an i), or a nonprinting character (the space character). Compare character. generic password A password other than an Internet password. gesture In Ink Services, a handwritten mark that is recognized as having a special meaning, such as, Select All, Cut, and Copy. GID Group ID. A unique identifier for a collection of users. In BSD, each user can belong to one or more groups. Each file-system object has an associated GID that is used to determine the object’s permissions. Each process has an associated group list. See also process GID. glyph code A number that specifies a particular glyph in a font. Fonts map character codes to glyph codes, which in turn specify individual glyphs. glyph direction The direction in which successive glyphs are read. GL The core OpenGL library. glyph index The order of a glyph in a line of display text. The leftmost glyph in a line of text has a glyph index of 0; each succeeding glyph to the right has an index one greater than the previous glyph. Compare edge offset. global coordinates The coordinate system where the origin is set at the top-left corner of the main viewing screen. Compare local coordinates. global dispatch queue A dispatch queue provided to your application automatically by Grand Central Dispatch (GCD). You do not have to create global queues yourself or retain or release them. Instead, you retrieve them using the system-provided functions. glyph orientation A value that specifies which direction (vertical or horizontal) glyphs should be drawn. glyph origin The point used to position a glyph when drawing. global socket filter In the kernel, a socket filter that is automatically enabled for sockets of the type specified. glyph outline The curves that make up the shape of the glyph. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 55 Glossary gradient A fill that varies from one color to another. See also axial gradient, radial gradient. group box In a dialog, a visual indication that certain controls belong together. Grand Central Dispatch GCD. group list In security, the list of groups to which the owner of a process belongs plus any additional groups added to the list programatically (for example, using the setgid command). If the file GID of a file system object matches the GID of any group in the group list, that group has group permissions for the object. See also file UID. grafport See graphics context. graph (1) in Quartz Composer, a of connected patches on the workspace. (2) In Core Audio, short for audio processing graph. graphics context An opaque data type (CGContextRef) that encapsulates the information Quartz uses to draw images to an output device, such as a PDF file, a bitmap, or a window on a display. The information inside a graphics context includes graphics drawing parameters and a device-specific representation of the paint on the page. Groups & Files list In Xcode, a view that contains a list of a project’s contents. GSS-API Generic Security Service Application Program Interface. An open-source API that can be used to adapt an application to use Kerberos. gutter In Xcode, a vertical strip on the left side of the content pane in the editor. You can use it to quickly locate items in a file. A gutter can display numbers, errors and warning, and breakpoints. graphics mode In QuickTime, the method by which two overlapping images are blended together to produce a composite image. HAL Hardware abstraction layer. An object-like interface between Core Audio objects and hardware. The hardware abstraction layer typically addresses hardware by means of an I/O Kit driver, but this is not a requirement. The HAL gives applications a consistent way to communicate with external devices—insulating them from the complexity of addressing multiple, specialized hardware drivers. graphics port A drawing environment defined by a CGContextRef for Quartz 2D. The drawing environment contains all the information needed to translate drawing operations from bits in memory to the appropriate destination format (onscreen pixels, PDF, PostScript). graphics state Defines the drawing parameter settings (line width, fill color, and many other parameters) for a specific graphics context. handler (1) In AppleScript, a named series of one or more script statements that are executed by calling its name. (2) A Java class used by Axis to process a SOAP message or a part of it in a specific way. For example, a handler can be implemented to perform authentication on the message’s sender before allowing it to be processed by the receiver. graphics world In QuickTime, a software environment in which a movie track or set of images may be defined before importing them into a movie. group (1) In security, a collection of users. See also GID. (2) In Xcode, a collection of related files in the Groups & Files list. See also smart group, source group. handler chain In WebObjects, a group of handlers that can be viewed as a unit. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 56 Glossary handler reference atom A QT atom of type 'hdlr' that specifies the media handler to be used to interpret a media structure. See also media, media handler, QT atom. helper tool A tool that executes some of an application’s functions as a separate process. In the case of security, a helper tool performs privileged operations for the application. See also setuid tool. hanging baseline The baseline used by Devanagari and similar scripts, where most of the glyph is below the baseline. Help Menu A menu that provides access to the onscreen help documentation for an application. help tag A brief text explanation that appears when the user leaves the pointer over an interface element for a few seconds. hanging glyphs A set of glyphs, usually punctuation, that typically extend beyond the left and right margins of the text area and whose widths are not counted when line length is measured. Help Viewer The simple browser used to display Apple Help HTML files. Hangul A Korean subscript that consists of blocks of component glyphs called Jamo, which are characters different from typical character clusters in that they are treated as singular units in memory; there are no principal characters and attachments. HFS Hierarchical File System. The Mac OS Standard file-system format, used to represent a collection of files as a hierarchy of directories (folders), each of which may contain either files or other folders. HFS is a two-fork volume format. Hardware Abstraction Layer See HAL. HFS+ Hierarchical File System Plus. The Mac OS Extended file-system format. This format adds support for filenames longer than 31 characters, Unicode representation of file and directory names, and efficient operation on very large disks. HFS+ is a multiple-fork volume format. hash Number derived from a string such that any change to the string produces a different number. hash algorithm See cryptographic hash function. head node The final node in an audio processing graph in terms of signal flow; the output node of a graph. See also audio unit, shared workgroup build. hierarchical browser The area in the Quartz Composer window used to view and navigate from one level to another in the patch hierarchy. Head Related Transfer Function See HRTF. hierarchical menu A menu that includes a menu item from which a submenu descends. Submenus offer additional menu item choices without taking up more space in the menu bar. Hierarchical menus are indicated with a triangle. headroom In audio, the range, expressed in decibels, between a standard reference signal level and the maximum allowable signal level (the ceiling). See also dynamic range. help book The collection of HTML files that provide onscreen help for a particular product. highlighting The display of text in inverse video or with a colored background. Highlighting in display text corresponds to a selection range in source text. Help button A button that opens Help Viewer to the help content appropriate for the context. A help button is a round button with a question mark. hints Information provided with a font that can be used to scale glyphs to various sizes. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 57 Glossary hint track A track in a QuickTime streaming movie that contains information for a packetizer about the data units to stream. See also stream. host time The clock time used by the computer running an audio application. hot spot (1) The portion of the pointer that must be positioned over a screen object for mouse clicks to have an effect on the object. (2) An area, typically in a VR presentation, that the user can click to invoke an action. histogram A diagram that shows the frequency of occurrences within a data set. In the graphics domain, histograms can be used to plot the frequencies of certain pixel intensities. HIToolbox Human Interface Toolbox. A collection of procedural APIs that apply an object-oriented model to windows, controls, and menus for Carbon applications. The HI Toolbox supplements older Macintosh Toolbox managers such as the Control Manager, Dialog Manager, Menu Manager, and Window Manager from Mac OS 9. hot zone The area of an onscreen object that the pointer’s hot spot must be within for mouse clicks to have an effect. HRTF Head related transfer function. Also called Anatomical Transfer Function , or ATF . A mathematical description of the frequency and phase filtering that takes place when an acoustic signal impinges on a person’s head and pinnae. The HRTF is used in DSP to add spatialization information to a signal. See also DSP, panning, spatialization. hit-testing The process of converting a location within a line of display text into a caret offset in the source text of that line. horizontal reflect A type of geometric operation that reflects an image about its y-axis. HTTP Hypertext Transfer Protocol. The client-server TCP/IP protocol used on the web for the exchange of HTML documents. horizontal shear In image processing, a filter that shifts pixels along the x-axis to create an effect that’s similar to physical shearing. HTTP adaptor A process (or a part of one) that connects WebObjects applications to a web server. host (1) The computer that is running (is host to) a particular program or service. The term is usually used to refer to a computer on a network. (2) In debugging, the computer that is running the debugger itself. In this context, the target is the machine running the application, kernel, or driver being debugged. HTTP server See web server. hybrid metapackage A metapackage that contains a distribution script. This type of installer package behaves as a distribution package when installed on computers running OS X v10.4 and later. On computers running earlier versions of the operating system, a hybrid metapackage behaves as a regular metapackage. See also distribution package, metapackage. host application A Mac app that loads and uses audio units. See also audio unit. host processor The microprocessor on which an application program resides. When an application is running, the host processor may call other, peripheral microprocessors, such as a digital signal processor, to perform specialized operations. hypertext Action media that contains a URL and takes the user to a website. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 58 Glossary hyphenation point An entry in an array of edge offsets in source text at which it is appropriate to break a line of display text. icon button A button that does not have a rectangular edge around it; the clickable region is the graphic (for example, the toolbar buttons in System Preferences windows). I/O Input/output. (1) The exchange of data between two parts of a computer system, usually between system memory and a peripheral device. (2) The software- or hardware-based audio inputs and outputs for a device. icon genre A group of icons that share similar visual design characteristics used to designate a particular category of items. IDE Integrated development environment. A program that typically combines text editing, compiling, and debugging features in one package in order to assist developers with the creation of software. I/O Catalog A dynamic database that maintains entries for all available drivers on a Darwin system. Driver matching searches the I/O Catalog to produce an initial list of candidate drivers. I/O Kit A kernel-resident, object-oriented environment in Darwin that provides a model of system hardware. Each type of service or device is represented by one or more C++ classes in a family; each available service or device is represented by an instance (object) of that class. ideal metrics Resolution-independent measurements used to describe how a glyph is drawn. Compare screen metrics. identification The process by which a process verifies that a person or entity is the same one it communicated with previously. Identification is in general faster than authentication and does not require interaction with the user. In Kerberos, for example, the authentication server authenticates a user and issues a credential (called a ticket-granting ticket ), which can be used later for identification so that reauthentication is not necessary. I/O Kit framework The framework that includes IOKitLib and makes the I/O Registry, user client plug-ins, and other I/O Kit services available from user space. It lets applications and other user processes access common I/O Kit object types and services. See also framework I/O module A module used by the printing system to provide a way to communicate with a printer using a standard interface for a transport type. identifier In AppleScript, series of characters that identifies a value or handler. Identifiers are used to name variables, handlers, parameters, properties, and commands. I/O Registry A dynamic database that describes a collection of driver objects, each of which represents an I/O Kit entity. As hardware is added to or removed from the system, the I/O Registry changes to accommodate the addition or removal. identity A digital certificate together with an associated private key. identity matrix In image processing, a transformation matrix that specifies no change in the coordinates of the source image. The resulting image corresponds exactly to the source image. See also transformation matrix. I/O service thread See interrupt service thread. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 59 Glossary identity transform An affine transform that, when applied to input coordinates, always returns the input coordinates. ignoring statement A control statement that lists a specific set of attributes to be ignored when AppleScript performs operations on text strings or sends commands to applications. idle sleep A sleep state that occurs when there has been no device or system activity for the period of time the user specifies in the Energy Saver pane of System Preferences. See also system sleep. IMA ADPCM Interactive Multimedia Association ADPCM. A lossy, 16-bit audio compression format that provides 4:1 compression. The format is sometimes referred to as IMA or IMA4 . See also ADPCM. ID reference form In AppleScript, a reference form that specifies an object by the value of its ID property. image A group of related pixels, often represented with a rectangular array of values. IEC International Electrotechnical Commission. An international standards organization, founded in 1906, that collaborates with ISO on defining a wide variety of perceptual coding formats. imageable area The part of the paper to which a printer can draw without the image being clipped. image bounding rectangle The smallest rectangle that completely encloses the filled or framed parts of a block of text. See also typographic bounding rectangle. IEEE Institute of Electrical and Electronic Engineers. An organization of electronics professionals that has established many technology and audio-related standards. Pronounced “eye triple-e.” image browser view The Image Kit view class (IKImageBrowserView ) that is optimized for browsing images. The user term is image browser . IEEE 1394 See FireWire. if statement A control statement that contains one or more Boolean expressions whose results determine whether to execute other statements within the if statement. image buffer An abstract buffer type that holds Core Video images. Pixel buffers, Core Video OpenGL buffers, and OpenGL textures derive from the CVImageBuffer type. IFF Interchange File Format. A flexible, chunk-based file format for storing media content. Developed by Electronic Arts, Inc., and the technical inspiration for Apple’s AIFF. Image Edit panel The Image Kit edit panel class (IKImageEditPanel ), which is optimized for editing images. The user term is Image Edit window . ifnet structure A data structure containing image format An image encoding standard that specifies the number of color channels and number of bits per channel. function pointers and data related to a particular network interface. ignore condition A state that triggers a breakpoint only if the condition is true. Image I/O A framework (ImageIO.framework ) that provides opaque data types for reading data from an image source and writing data to an image destination. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 60 Glossary Image Kit A programming interface that supports browsing, viewing, and editing images and browsing and controlling Core Image filters. (2) In acoustics, the ratio of average sound pressure to particle velocity over a given surface area and at a given frequency. image mask A bitmap that specifies an area to paint, but not the color. An image mask acts like a stencil to specify where to place color on the page. implicitly specified subcontainer An object container that can be specified in an AppleScript script by context, rather than by an explicit reference. For example, explicitly specifying a word object in a document object might require this script reference: fourth word of text of front document . But if the application provides support for implicitly specifying the text container, the script reference can be simplified to this: fourth word of front document . image sequence A series of visual representations usually represented by video over time. Image sequences may also be generated synthetically, such as from an animation sequence. image track Any track in a QuickTime movie that contains visual images. The term particularly applies to video tracks that contain VR data. implicit run handler In AppleScript, all the statements at the top level of a script except for property definitions, script object definitions, and other handlers. A single script object can include an explicit run handler or an implicit run handler, but not both. image unit A Core Image filter that is packaged for distribution as anNSBundle object. Image units contain one or more filters for manipulating image date. See also SIMD. image well A rectangular, recessed area that displays an icon or picture and that serves as a drag-and-drop target. imposed width A control feature that forces a specific width onto the glyphs of a style run, regardless of its text content or other style properties. imaging system The system used to render text or graphics. inactive In iOS, used to describe an audio session state in which playback or recording cannot proceed. Compare active. immediate mode The practice of OpenGL executing commands at the time an application issues them. To prevent commands from being issued immediately, an application can use a display list. inactive window A window that is in the background of other windows. Although some of its controls can be activated (click-through) and it can be a drag-and-drop target, an inactive window is not the focus of the user’s attention. immersive audio Sound reproduction or generation that seems to surround a listener. See also surround sound. impedance (1) In electronics, the amount of opposition a circuit presents to an AC (alternating current) signal at a given frequency. Impedance includes both a resistive (frequency-independent) and a reactive (frequency-dependent) component. in-band Said of communication on a socket or interface that contains actual data destined for the endpoint (for example, send and recv calls). Compare out-of-band. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 61 Glossary inclusion/exclusion result See inclusion/exclusion searching. information property list A property list that contains essential configuration information for bundles such as kernel extensions. A file named Info.plist (or a platform-specific variant of that filename) contains the information property list and is packaged inside the bundle. See also bundle, property list. inclusion/exclusion searching Unranked searching where the result simply includes documents that match the query and excludes documents that don’t. Inclusion/exclusion searches tend to be faster than ranked searches. Search Kit supports inclusion/exclusion searches. See also relevance-based result. information retrieval See signal-to-noise ratio. Info window A window in the Finder and other applications that presents information about and provides settings for a particular entity. In Interface Builder, an Info window has settings related to the attributes and connections for the associated user interface object. In Xcode Info windows, users can manipulate information about a project item, such as files, targets, and the project itself. index In Search Kit, a memory- or file-based sequential collection of the terms in one or more documents. In addition to terms, Search Kit indexes contain context information that specifies which documents each term belongs to, along with term and document metadata useful during display of search results. Search Kit performs its searching and analysis on indexes. See also inverted index, inverted-vector index, vector index. inheritance (1) In object-oriented programming, the ability of a superclass to pass its characteristics (methods and fields) on to its subclasses, allowing subclasses to reuse these characteristics. (2) In AppleScript, the ability of a child script object to take on the properties and handlers of a parent object. index group A short-lived collection of one or more indexes; the target of a search. An index group corresponds to one or more aspects of the corpus of documents you want to search. For example, one index in a group might contain document titles, while another contains the body text of those same documents. An index group can also comprise indexes of multiple corpora. See also corpus. inheritance attribute In Mach, a value indicating the degree to which a parent process and its child process share pages in the parent process’s address space. A memory page can be inherited as copy-on-write, shared, or not at all. index reference form In AppleScript, a reference form that specifies an object by describing its position with respect to the beginning or end of a container. inheritance chain The hierarchy of objects that AppleScript searches to find the target for a command or the definition of a term. indicator The part of a control that visually represents its value. For example, on a scroll bar control, the scroller is the indicator. initialize (1) In Core Audio, to configure an audio unit for use. (2) In AppleScript, to create a script object from the properties and handlers listed in a script object definition. AppleScript creates a script object when it runs a script or handler that contains a script object definition. info plist See information property list. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 62 Glossary initialize In Core Audio, to configure an audio unit for use. Ink window The Ink toolbar plus the Ink pad. The window allows the user to control various aspects of Ink and to enter Ink input. initializing a script object The process of creating a script object from the properties and handlers listed in a script object definition. AppleScript creates a script object when it runs a script or handler that contains a script object definition. Ink writing guides In the Ink technology, the lines (alternating solid and broken) that appear when a user is writing directly into an application. in-line data Data that’s included directly in a Mach message, rather than referred to by a pointer. Compare out-of-line data. Ink In the Ink technology, raw data that represents the input drawn by the user with the stylus. inline input An input method that allows the user to enter text directly into a document. In inline input, entry and conversion of characters take place at the current line position—where the converted text is intended to appear—rather than in a separate window. Inline input is the principal example of the kind of text service supported by the Text Services Manager. Compare bottomline input. Ink input method In the Ink technology, a low-level task that takes the user input and then draws the appropriate data on the screen. In effect, converting physical pen strokes into electronic ink. Ink pad The part of the Ink window that provides a simple note pad interface where handwritten input is converted into editable text. Ink phrase In the Ink technology, the grouping of ink data created by the recognition system, based on the timing and spacing of the user’s handwriting. In Roman languages, an Ink phrase is typically a short string of characters with no spaces between them such as an individual character, several characters, a word, or, an entire URL. For most situations, an Ink phrase is equivalent to a word. input audio queue See audio queue. input map A QuickTime data structure that describes where to find information about tracks that are targets of a modifier track. See modifier track. input method A software module for multiple-byte script systems that converts phonetic or syllabic characters, entered from a keyboard, into ideographic or other complex representation of text. Because multiple-byte script systems have too many characters to be entered directly from a keyboard, the input method uses a conversion technique, such as translating sequences of phonetic characters that are typed into a special input window. For example, the Japanese script system provides software for transcribing Kana (phonetic Japanese) into ideographic Kanji. Ink server The component of Ink technology that manages the recognizer, the language model, and the Ink window. Ink text In the Ink technology, words written in electronic ink. Ink text object An opaque object that contains information about an Ink phrase. Ink toolbar The toolbar that appears at the top of the Ink window. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 63 Glossary input order The order in which characters are written or entered from a keyboard. The input order of a line of text can differ from its display order. Compare display order. installation requirement A condition that the target computer or volume of an installation must meet in order for the installation to take place. The two types of installation requirements are system requirements and volume requirements. input source A source of asynchronous events for a thread. Input sources can be port-based or manually triggered and must be attached to the thread’s run loop. installation volume The volume (or mountpoint) onto which an installation package is to be installed. install choice An option users can select or deselect as part of the installation process to specify whether a product component is to be installed. insertion point (1) The point at which text or other data is to be inserted or deleted. An insertion point is specified by a single caret position. Compare caret. (2) In AppleScript, the location where another object or objects can be added. install customization pane A pane users see while interacting with the Installer application if the package being installed allows the user to customize the installation by choosing the product components to be installed. See also product component, product package. installation action A task to be performed before or after an installation. PackageMaker defines several installation actions, including Quit Application and Show File in Finder. install experience The tasks a user needs to perform in order to install a product on their computer. installation destination The directory in which Installer places a package’s payload. install operation Installation activity performed by an executable file that is invoked at a specific point during the installation process. installation host The computer onto which a package is to be installed. installation package A file package with the .pkg or .mpkg extension. Installation packages (also known as packages) contain products or product components (known as the package’s payload) and installation information used by the Installer application and Remote Desktop to place product files on a file system. install operation executable An executable file that is invoked by Installer during an installation, before or after copying a package’s payload to the installation destination. Installer package database System-level database of all the installation packages installed by the Installer application. installation property Information in an installation package that specifies an installation requirement or an installation process detail, such as whether relocation is allowed. instance In object-oriented languages such as Java and Objective-C, an object that belongs to (is a member of ) a particular class. Instances are created at runtime according to the specification in the class definition. installation receipt A token that Installer uses to determine whether a component has already been installed on an installation volume. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 64 Glossary instant mousing area In the Ink technology, an area in which stylus input is interpreted as mouse input; the system “instantly” interprets the stylus as a mouse in these special places and ink is not generated. interface KEXT A network kernel extension that provides routines specific to a particular family of interfaces, such as ARP equivalence routines. interface layer A layer above the driver layer containing interface KEXTs, interface filters, and protocol plumbers. instrument A data-gathering agent developed using the Instruments application. Instruments collect performance information about an application or an entire system. interface object In Interface Builder, an object in a nib file that is created for your application at load time. Interface objects can consist of both visual objects (such as windows, views, and menus) and nonvisual objects (such as controllers). Instruments An integrated performance analysis and debugging tool. Instruments lets you gather a configurable set of metrics while your application is running, providing you with visualization tools to analyze the data and see performance problems and potential coding errors within your software. interlacing A video mode that updates half the scan lines on one pass and goes through the second half during the next pass. interleaved data In image processing, arrays of dissimilar data that are grouped together, such as vertex data and texture coordinates. Interleaving can speed up data retrieval. Instruments application See Instruments. instrument unit In Core Audio, an audio unit of type'aumu' that takes sound bank data and MIDI control data as inputs, and outputs digital audio. interleaved image format A format that encodes each color (and alpha) channel, one after the other, for every pixel. In contrast to planar image formats which encode an entire image using one color at a time, interleaved image formats alternate through each channel, encoding data for all channels simultaneously within each pixel. For example, an interleaved image would encode an image in a RGBRGBRGB fashion, whereas a planar image would encode the same image as RRRGGGBBB. integer A positive or negative number without a fractional part. interface The calling conventions by which a client accesses a service. An interface provides a level of abstraction that hides the implementation details of the service from the client. Interface Builder An application that helps you easily create application menus, windows, dialogs, palettes, and other standard Aqua interface elements. interleaving (1) In digital audio, converting a set of data streams representing discrete channels into a single stream that retains the capacity to be converted back to separate channels. A synonym for multiplexing . In Audio Converter Services and in audio file formats such as CAF, interleaving involves placing one sample from each channel in sequence such that a set of coincident samples, one from each channel represented in the data stream, appears in interface filter A filter attached to a particular interface Unicode decomposition. An interface filter alters in-band and out-of-band communication specific to a given interface. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 65 Glossary each frame. Compare deinterleaving. (2) In QuickTime, a technique in which sound and video data are alternated in small pieces, so the data can be read off disk as it is needed. Interleaving allows for movies of almost any length to have little delay on startup. interrupt handler A routine executed when an interrupt occurs. Interrupt handlers typically deal with low-level events in the hardware of a computer system, such as a character arriving at a serial port or a tick of a real-time clock. interrupt service thread A thread running in kernel space for handling I/O that is triggered by an interrupt, but does not run in an interrupt context. Also called an I/O service thread . internally framed In audio, describes a variable-bit-rate audio format where information about the sizes of the frames is included in the audio data stream. Compare externally framed. See also webpage template, variable bit rate. inverse relationship A relationship that goes in the reverse direction of another relationship. Also known as a back relationship . internationalization The design or modification of a software product, including its online help and documentation, to facilitate localization. Internationalization of software typically involves writing or modifying code to make use of locale-aware operating-system services for appropriate localized text input, display, formatting, and manipulation. See also localization. inversion In graphics, an operation that produces original coordinates from transformed ones. inverted index In Search Kit, an index containing terms, as keys, mapped to references to the documents they appear in. The index is sorted by its keys. “Inverted” means that the documents are found by matching on terms, rather than the other way around. See also index, inverted-vector index, vector index. Internet password A password for an Internet server, such as a web or FTP server. Internet password items on the keychain include attributes such as the security domain and IP address. inverted-vector index In Search Kit, an index containing terms mapped to document URL objects representing the documents that the terms appear in, as well as document URL objects mapped to the terms that each document contains. See also index, inverted index, vector index. interpolation The calculation of intermediate values relative to known beginning and ending values. interprocess communication See source control. interrupt An asynchronous event that suspends the currently scheduled process and temporarily diverts the flow of control through an interrupt handler routine. Interrupts can be caused by both hardware (I/O, timer, machine check) and software (supervisor, system call, or trap instruction). IP filter A filter that alters IP traffic each time it enters the protocol stack. By its very nature, an IP filter can only filter in-band communication. IPC Interprocess communication. A set of programming interfaces that enables a process to communicate data or information to another process. Mechanisms for IPC exist in the various layers of the system, from Mach messaging in the kernel to distributed notifications and Apple events 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 66 Glossary in the application environments. Each IPC mechanism has its own advantages and limitations, so it is not unusual for a program to use multiple IPC mechanisms. Other IPC mechanisms include pipes, named pipes, signals, message queueing, semaphores, shared memory, sockets, the Clipboard, and application services. standards, including those for multimedia data formatting and transmission, such as JPEG, MP3, and MPEG. Pronounced “EYE-so.” iSync A tool for synchronizing address book and calendar information. item (1) In Launch Services, an application, document, or URL to be operated on. (2) In AppleScript, a value in a list or record. An item can be specified by its offset from the beginning or end of the list or record. iOS Dev Center An Apple developer center that provides all the resources needed to develop iOS applications. Access to this developer center requires an ADC membership. See also user focus. item information record A data structure of type LSItemInfoRecord , used by Launch Services to return information about an item. iOS Developer Program A program that allows you to develop iOS applications, test them on devices, and distribute them to your customers through the App Store. J2EE Java 2 Platform, Enterprise Edition. A specification that defines a platform for the development and deployment of web applications. It describes an environment under which enterprise beans, servlets, and JSP pages can share resources and work together. iOS Simulator application An application that simulates the iOS runtime environment and user experience in OS X for testing iOS applications in early stages of development. IPL Interrupt priority level. A means of basic synchronization on uniprocessor systems in traditional BSD systems, set using thesplmacro. Interrupts with lower priority than the current IPL are not acted upon until the IPL is lowered. In many parts of the kernel, changing the IPL in OS X is not useful as a means of synchronization. New use ofsplmacros is discouraged. See also spl macro. Jamo An individual phonetic glyph in the Korean script that is transformed and combined into clusters called Hangul. JAR Java archive. A file created using the jar utility (and saved with the .jar extension) that contains all the files that make up a Java application. Java A development environment for creating applications that can be seen in both standalone and networked environments. IR Information retrieval. The process of locating information based on a well-defined information need. An information retrieval system consists of a corpus, one or more indexes of its content, a query interface, a search system, and a results interface. Java Client A WebObjects development approach that allows you to create graphical user interface applications that run on the user’s computer and communicate with a WebObjects server. ISO A standards organization, called International Organization for Standardization in English, that formulates and promotes industrial and commercial Java Foundation Classes See JFC. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 67 Glossary JavaMonitor A tool used to configure and maintain deployed WebObjects applications capable of handling multiple applications, application instances, and applications hosts at the same time. join In relational databases, an operation that provides access to data from two tables at the same time, based on values contained in related columns. joinable thread A thread whose resources are not reclaimed immediately upon termination. Joinable threads must be explicitly detached or be joined by another thread before the resources can be reclaimed. Joinable threads provide a return value to the thread that joins with them. Java Native Interface See source file. Java virtual machine See source group. JAXP Java API for XML Processing. A specification that provides an API for processing XML documents. JPEG Joint Photographic Experts Group. An international standard for compressing still images. This standard supplies the algorithm for image compression. The version of JPEG supplied with QuickTime complies with the baseline ISO standard bitstream, version 9R9. This algorithm is best suited for use with natural images. JBoss A Java-based open-source application server capable of deploying J2EE-based applications. JBoss provides many useful features in addition those defined in the J2EE standard, including support for clustering, session replication, mail, and security. JDBC Java Database Connectivity. An interface between Java platforms and databases. JSP JavaServer Pages. A technology that facilitates the development of dynamic web pages and web applications that use existing components, such as JavaBeans and WebObjects components. JDBC adaptor A datasource adaptor that allows WebObjects applications to connect to JDBC-compliant database management systems. JFC Java Foundation Classes. A set of graphical user interface components and services written in Java. The component set is known as Swing . justification The process of typographically expanding or compressing a line of text to fit a text width. jitter In audio, time-based inconsistencies in the clock signal or clock component in a digital signal stream. In digital audio, jitter can result in audible distortion. justification gap The difference in the length of a line before and after justification. justification override The degree to which a text layout system should override justification behavior for glyphs in a style run. JMS Java Message Service. A Java-based programming interface that implements an asynchronous message-exchange system. It facilitates the development of message-based applications. JMS is part of the J2EE platform. justification priority The priority order in which classes of glyphs are processed during justification. JNI Java Native Interface. A technology for bridging C-based code with Java. JVM Java virtual machine. The runtime environment for executing Java code. This environment includes a just-in-time bytecode compiler and utility code. job ticket The top-level ticket used for a print job. See also ticket. kashida An extension-bar glyph that is added to certain Arabic glyphs during justification. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 68 Glossary KDC Key distribution center. In Kerberos, the sum of two separate software processes: the ticket-granting server and the authentication server. number. An image process that uses a kernel typically takes these numbers within the kernel and applies them to the image by undergoing a series of arithmetic operations between the kernel values and the image pixel intensity values. KDP The kernel shim used for communication with a remote debugger ( gdb ). kernel crash An unrecoverable system failure in the kernel caused by an illegal instruction, memory access exception, or other failure rather than explicitly triggered as in a panic. Compare panic. kerberized service A service that has been configured to accept Kerberos tickets for identification. Kerberos An industry-standard protocol created by the Massachusetts Institute of Technology (MIT) to provide authentication over a network. It is a symmetric-key, server-based protocol and is used widely in Macintosh, Windows, and UNIX networks. kernel extension See KEXT. kernel mode See supervisor mode. kernel module See KMOD. kernel panic See panic. Kerberos ticket A credential used to identify a user who has been previously authenticated so that reauthentication is not needed. In Kerberos, the KDC (key distribution center) issues the user a TGT (ticket-granting ticket) when they first authenticate. Thereafter, when they need to access a secure server, they present the ticket-granting ticket to the KDC and are issued a ticket, which they present to the secure server as identification. See also authentication, identification. kernel port A Mach port whose receive right is held by the kernel. See also task port, thread port. kernel space The protected memory partition in which the kernel resides. See also user space. kerning An adjustment to the normal spacing that occurs between two or more specifically named glyphs, known as the kerning pair . kerning pair Two specifically named glyphs that are kerned together by a set amount. See also kerning. Kerberos Ticket Viewer A utility available through the Keychain Access utility that shows any Kerberos tickets in use on the system and enables the user to renew or destroy a ticket or change a ticket’s password. KEXT Kernel extension. A dynamically loaded bundle that extends the functionality of the kernel. The I/O Kit, file system, and networking components of Darwin can be extended by KEXTs. kernel (1) The complete OS X core operating-system environment, which includes Mach, BSD, the I/O Kit, file systems, and networking components. Also called the kernel environment . (2) In image processing, a grid of numbers used in both convolution and morphological operations (such as dilation and erosion). It is typically represented as a square grid (or matrix) whose height and width are both odd, such as a 3 x 3 grid. Each cell in the grid contains a KEXT binary See KMOD. key (1) An arbitrary value (usually a string) used to locate a piece of data in a data structure such as a dictionary. (2) In security, a piece of secret information required to decode an encrypted message. In modern cryptographic methods, it is usually a lengthy integer. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 69 Glossary keyboard and font synchronization A process by which the current keyboard script is compared to the script of the font at the current insertion point. If the two don’t match, one or the other is changed so the two scripts are the same. In most cases, when the user starts typing, the font is automatically replaced with one belonging to the keyboard script, although it is possible to synchronize in the other direction. address attribute. The password or other secret stored as a keychain item is encrypted and is inaccessible when the keychain is locked. When the keychain is unlocked, the secret can be read by the trusted applications listed in the item’s access object and by the user (with the Keychain Access utility). The attributes are not currently encrypted. Keychain Services The programming interface used to create, delete, and modify keychains and keychain items. keyboard focus The state in which a window or control receives keystrokes. Keyboard input is directed to one window (and one control within the window) at a time. key distribution center See KDC. key-down event An event indicating the user pressed a key. keyboard glyph A graphical representation of a physical key that doesn’ havet a character equivalent (such as a function key or the Shift key). key frame In QuickTime, a sample in a sequence of temporally compressed samples that does not rely on other samples in the sequence for any of its information. Key frames are placed into temporally compressed sequences at a frequency that is determined by the key frame rate. Typically, the term key frame is used with respect to temporally compressed sequences of image data. See also key frame rate, stencil buffer. keyboard script The script system for keyboard input. It determines the character input method and the mapping of keystrokes to character codes. The keyboard script may be different from the script used to display text. keychain A database in OS X and iOS used to store encrypted passwords, private keys, and other secrets. It is also used to store certificates and other nonsecret information that is used in cryptography and authentication. The Keychain Manager and Keychain Services are public APIs that can be used to manipulate data in the keychain, and the Keychain Access utility is an application that can be used for the same purpose. See also keychain item keyframe animation An animation that specifies an array of values that an animation uses as sequential targets. key frame rate The frequency with which key frames are placed into temporally compressed data sequences. See also key frame. keypath A chain of keys supported by key-value coding that allows for the traversal of relationships between enterprise objects. See also KVC. Keychain Access A utility that allows users to create, delete, and modify keychains and keychain items. keychain item A secret that is encrypted and protected by the keychain, plus its associated attributes and access object. Each keychain item has a class that determines what attributes it has; for example Internet password items include an IP key-repeat The repetition of a character when the user holds down a key representing that character. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 70 Glossary key signing In public key cryptography, electronically stating your trust that a public key really belongs to the person who claims to own it, and potentially that the person who claims to own it really is who he or she claims to be. label font The font used for labels with controls such as sliders and icon bevel buttons. It is 10-point Lucida Grande Regular. Lanczos resampling A commonly used math routine for resampling values in a data set. vImage uses it as a default technique for determining new pixels that did not previously exist in the input image. key-up event An event indicating the user released a key. key-value coding See KVC. key window The window that currently accepts input from the keyboard. language The written and spoken methods of combining words to create meaning used by a particular group of people. keyword (1) A word that is an explicit part of a programming language; also called a reserved word . (2) In a PostScript printer description file, a string used to describe a printer—for example, *PageSize and *Font . (3) A four-character code used by the Apple Event Manager to identify a specific descriptor within an Apple event. Last Resort font A collection of glyphs that represent types of Unicode characters. These glyphs can be used as a backup to any other font; if the font cannot represent any particular Unicode character, the appropriate “missing” glyph from the Last Resort font can be used instead. latency In digital audio processing, the time required for an audio sample to proceed from an input to a corresponding output. Total latency, depending on the scope of the system under consideration, can include unavoidable hardware latency (sometimes called I/O latency ), safety offset latency (required for robust driver operation), and buffer latency (typically software controlled; dependent on digital signal processing requirements). kind string A string used (in the Finder’s Get Info window, for example) to characterize the general nature of an item, such as Application, Folder, Alias, JPEG Picture, or QuickTime Movie. KMOD Kernel module. A binary in Mach-O format that is packaged in a KEXT (kernel extension). A KMOD is the minimum unit of code that can be loaded into the kernel. Also called a KEXT binary . See also KEXT. launch To start up an application that was not previously running. Compare activate. KPI Kernel programming interface. A group of opaque data types and accessor functions designed to maintain binary compatibility across OS releases. launch options A set of flags specifying the manner in which an application is to be opened. KVC Key-value coding. A mechanism used in Cocoa and WebObjects for accessing object properties indirectly by key. See also keypath. launch sequence The sequence of operations performed by an application immediately on being launched, indicated visually to the user by the application’s icon bouncing in the Dock. labeled parameter In AppleScript, a parameter that is identified by a label. See also positional parameter. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 71 Glossary Launch Services A Mac app programming interface that enables a running program to open other applications, documents, or URLs in a way similar to the Finder or the Dock. Layout pane A pane in the Print dialog that lets the user set the number of pages per sheet and the type of border on a page. LDAP Lightweight Directory Access Protocol. A standard client-server protocol for accessing online directory services. Launch Services database The data structure in which Launch Services records information about available applications and the kinds of documents or URLs they are capable of opening. leading edge The edge of a glyph that is encountered first when reading text of that glyph’s language. For glyphs of left-to-right text, the leading edge is the left edge; for glyphs of right-to-left text, the leading edge is the right edge. launch specification A data structure of type LSLaunchFSRefSpec or LSLaunchURLSpec , used to specify to Launch Services the manner in which an item or items are to be opened. leading frames In audio data format conversion, frames of audio data that precede, in time, the nominal starting frame for an input stream. See also priming. Compare trailing frames. layer In QuickTime, a mechanism for prioritizing the tracks in a movie or the overlapping of sprites. When it plays a movie, QuickTime displays the movie’s tracks according to their layer—tracks with lower layer numbers displayed first; tracks with higher layer numbers are displayed over those tracks. leaf atom In QuickTime, an atom that contains only data and no other atoms. left-side bearing The white space between the glyph origin and the visible beginning of the glyph. layer-backed view An instance of an NSView object that uses a Core Animation layer to cache its drawing content. The view is responsible for managing the layer tree; the developer should not manipulate the layer tree directly. level A description of the nominal audio signal strength resulting from a given input level and gain in an audio device or system. Level within analog audio circuitry is often measured in dBu. The instantaneous signal strength, for any nominal level, can vary from the noise floor to the dynamic ceiling. Professional “line level” typically indicates a nominal level of +4 dBu, while “consumer level” typically indicates a nominal level of –10 dBu. See also ceiling, dBu, noise floor. Compare volume. layer context An offscreen drawing destination (CGLayerRef) designed for optimal performance. Introduced in OS X v10.4, a layer context is a much better choice for offscreen drawing than a bitmap graphics context. layer-hosting view An instance of an NSView object that hosts a Core Animation layer tree. The developer is responsible for managing the layer tree directly. level compression Reduction of the dynamic range of an audio signal, typically by reducing the gain ratio for amplitudes above a specific level. Compare limiting. layout cache A cache that contains all the information ATSUI needs to draw a range of text associated with a text layout object. This includes caret positions, the memory locations of glyphs, and other information needed to lay out the glyphs. level indicator A control that displays the level or capacity of something. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 72 Glossary level of trust The confidence one can have in the validity of a certificate, based on the certificates in its certificate chain and on the certificate extensions the certificate contains. The level of trust for a certificate is used together with the trust policy to answer the question “Should I trust this certificate for this action?” line and layout attributes Attributes that specify how the lines of text associated with the text layout object are displayed and formatted. Line attributes control an individual line of text; layout attributes control all of the text associated with a text layout object. linear In audio, describes a transfer function whose output signal is directly proportional to the input. LFE Low frequency effect. One of the six typical channels in 5.1 Surround Sound. The LFE channel covers the bottom two or three octaves of audio and is typically used to enhance the realism of sound effects such as explosions. linear gradient See axial gradient. linear PCM See LPCM. line breaking The process of determining the proper location at which to truncate a line of text so that it fits within a given text width. library UNIX feature for monitoring low-level system events. lifebeat Status message sent by WebObjects applications to wotaskd to report their activity. The four types of lifebeat messages are: has started, is alive, will stop, and will crash. line cap The style that Quartz uses to draw the endpoint of a line—butt, round, or projecting square. line dash pattern In drawing, the repeating series of line segments and spaces used to paint a dashed line. lifetime In AppleScript, the period of time over which a variable or property is in existence. line direction The direction in which text in a particular language is written and read. The English language has a left-to-right line direction; Arabic and Hebrew have a (primarily) right-to-left line direction. ligature A glyph that is created when two or more characters are combined to create a new character. ligature decomposition The breaking up of a ligature into its component glyphs during justification so that the individual glyphs may more evenly occupy the space allotted to the ligature. line join The style that Quartz uses to draw the junction between connected line segments—miter, round, or bevel. ligature splitting The division of a ligature for hit-testing purposes into regions corresponding to each of its component glyphs. line length The distance, in points, from the origin of the first glyph on a line through the advance width of the last glyph. limiter In audio, circuitry or software that limits signal amplitude to a user-defined maximum. Compare level compression. line width The total width of a line, expressed in user space units. list In AppleScript, an ordered collection of values. limiting In audio, the process of preventing signal amplitude from exceeding a user-defined maximum. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 73 Glossary list view A control for displaying data in a list. The primary list may by accompanied by additional columns that display secondary attributes about that items in the list. Hierarchies are presented through the use of disclosure triangles. this thread is the only one that can modify the data during this period. Some lock variants such as read-write locks allow multiple threads to hold a single lock under certain conditions. See also mutex lock literal In AppleScript, a value that evaluates to itself. locked A keychain state in which no key is available in memory to decrypt the passwords and other secrets protected by the keychain. When an application attempts to retrieve a secret from a locked keychain, the user is prompted for a password. The login keychain is unlocked automatically at login if its password matches that of the user’s login account. There is no way to extract secrets from a locked keychain without providing the keychain’ sassword. ’ All of a users keychains lock automatically when the user logs out. load balancing A technique used to distribute user-load among the instances of an application. When multiple instances of an application are running and a new user accesses the application, the WebObjects adaptor uses one of several algorithms to determine which instance to forward the request to. local coordinates The coordinate system for a window, where the origin is set at the upper-left corner of the window’s content region. Compare global coordinates. locking A mechanism to ensure that data isn’t modified by more than one user at a time and that data isn’t read as it is being modified. localization The adaptation of a software product, including its online help and documentation, for use in one or more regions of the world, in addition to the region for which the original product was created. Localization of software can include translation of user interface text, resizing of text-related graphical elements, and replacement or modification of user interface images and sound. See also internationalization. login keychain A keychain automatically created for a new login account. The login keychain is automatically unlocked at login if its password matches that of the user’s login account. log statement In AppleScript, a script statement that reports the value of one or more variables to the Event Log pane of a script window, and to the Event Log History window, if it is open. localize See localization. lookup table A data structure used to quickly make computations or retrievals of certain values. In image processing, it is used to store precalculated values of an equation instead of calculating the value each time it is requested. For example, if the equation is y = 2x , and you know that there are at most n distinct values, then you can create an array of size n (one for each input) that stores the precalculated local variable In AppleScript, a variable that is available only in the handler in which it is defined. Variables that are defined within handlers are local unless they are explicitly declared as global variables. lock A data structure used to synchronize access to a shared resource. The most common use for a lock is in multithreaded programs where multiple threads need access to global data. Generally, only one thread can hold the lock at a time; by convention, 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 74 Glossary value of the equation for the corresponding input (for example, = 0,  = 2,  = 4, ... [n] = 2n ). Mach A central component of the OS X kernel that provides such basic services and abstractions as threads, tasks, ports, interprocess communication (IPC), scheduling, physical and virtual address space management, virtual memory, and timers. loop (1) A series of code statements that is repeated. (2) In audio, an excerpt of a recording, often a few seconds long or shorter, intended to be played repeatedly as part of a larger composition. Mach-O Mach object file format. The preferred object file format for OS X. See also PEF. Mach port dispatch source A dispatch source used to process events arriving on a Mach port. loopback In WebObjects, a mechanism that allows you to open a connection to a computer that does not go over the network. Mach server A task that provides services to clients, using a MIG-generated RPC interface. See also MIG. loop variable In AppleScript, a variable whose value controls the number of times the statements in a repeat statement are executed. MacinTalk synthesizer The built-in speech synthesizer available in OS X. lossless compression Data size reduction without loss of information. Common lossless audio compression formats include FLAC (free lossless audio codec) and Apple Lossless. Compare lossy compression. macro patch A Quartz Composer patch that contains other patches. A macro is similar to a subroutine in a traditional program. A macro can nest other macros within it. A macro is visually distinguished from a nonmacro patch by its shape—macros have squared-off corners and other patches have rounded corners. lossy compression Data size reduction that entails loss of information. Common lossy audio compression formats include MP3, AAC, and IMA ADPCM. See also perceptual coding. Compare lossless compression. magic cookie In digital audio, an opaque data structure for transporting audio format metadata. For audio formats that use them, such as AAC, a magic cookie is produced during encoding, accompanies the data stream that it describes, and is employed during decoding. Magic cookie data is not accessed directly, but rather via a codec-specific interface. loudness A subjective term to describe perceived sound intensity. When SPL (sound pressure level) increases by 10, loudness approximately doubles. Compare gain, volume. LPCM Linear pulse code modulation. A linear and lossless uncompressed audio data format. PCM is usually assumed to mean linear PCM , but sometimes the adjective linear is used to differentiate from nonlinear PCM formats. See also PCM. main event loop In Carbon, the code loop where the application spends most of its time. The application is blocked while waiting for events. When an event occurs, the application processes it and then returns to the blocked state. main thread A special type of thread created when its owning process is created. When the main thread of a program exits, the process ends. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 75 Glossary main window The window that is the focus of the user’s actions. It may accept keyboard input itself or may work in conjunction with a key window. For example, a text editing document would be a main window when a user is actively typing or modifying text in it. manual install A user-driven installation process. Users drag a product’s files to a location of their choosing in their file system. Compare window. many-to-many relationship In relational databases, a relationship in which each record in the source entity may correspond to more than one record in the destination entity, and each record in the destination may correspond to more than one record in the source. For example, an employee can work on many projects, and a project can be staffed by many employees. In Enterprise Objects, a many-to-many relationship is composed of multiple relationships. See also relationship. major version A framework version specifier designating a framework that is incompatible with programs linked with a previous version of the framework’s dynamic shared library. Compare minor version. makefile A specification file used by a build tool to create an executable version of an application. A makefile details the files, dependencies, and rules by which the application is built. map To translate a range of memory in one address space (physical or virtual) to a range in another address space. The virtual-memory manager accomplishes this by adjusting its VM tables for the kernel and user processes. managed files The files stored in a source control repository. managed install An Installer-driven installation process. Users open an installer package in the Installer application, which performs all installation tasks. margins The left, right, top, and bottom sides of the text area. matching See device matching, driver matching management tool An HTML-based application through which an application-server configuration can be modified. It also allows for the viewing of statistics of resources and services deployed on application servers, starting and stopping services, and adding topics, queues, and data sources. matching dictionary A dictionary of key-value pairs that describe the properties of a device or other service. The values in a matching dictionary are compared against those in a driver personality during device matching. matrix A collection of numbers arranged in a grid. It can be thought of as the mathematical equivalent of a two-dimensional array. Much like two-dimensional arrays, matrices are composed of rows and columns with their elements referred to as cells . See also transformation matrix. manager In Carbon, a library or set of related libraries that define a programming interface. man-in-the-middle attack An attack on a communication channel in which the attacker can intercept messages going between two parties without the communicating parties’ knowledge. Typically, the man in the middle substitutes messages and even cryptographic keys to impersonate one party to the other. matte A defined region of a movie display that can be clipped and filled with another display. mbuf A data structure containing data about a network packet. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 76 Glossary media A data structure that contains information that describes the data for a track in a movie. Note that a media does not contain its data; rather, a media contains a reference to its data, which may be stored on disk, CD-ROM disc, or any other mass storage device. Also called a media structure . physical memory in response to page faults. Thus, the disk file serves as backing store for the code or data not immediately needed in physical memory. memory object An object managed by a pager that represents the memory, file, or other storage that backs a VM object. See also pager. media folder The video directory on a DVD disc volume. See VIDEO_TS. memory protection A system of memory management in which programs are prevented from being able to modify or corrupt the memory partition of another program. media handler A piece of software that is responsible for mapping from the movie’s time coordinate system to the media’s time coordinate system. The media handler also interprets the media’ data. s The data handler for the media is responsible for reading and writing the media’ data. s See also data handler. menu A user interface element that displays a list of possible selections to the user. menu bar The strip at the top of the user’s primary display that contains menu titles. It includes system and application menus. media ID A unique identifier assigned to a media folder by DVD Playback Services. This identifier can be used as a key when saving information about media playback, such as bookmarks. menu ID A unique ID that identifies a menu. menu item One of the choosable options displayed in a menu. memory cursor An object that lays out the buffer ranges in a memory descriptor in physical memory, generating a scatter/gather list suitable for a particular device or DMA engine. The object is derived from the IOMemoryCursor class. See also DMA, memory descriptor. menu item index A one-based index that identifies a particular menu item in the menu. A menu item index of 3 indicates the third item in the menu. message A unit of data sent by one task or thread that is guaranteed to be delivered atomically to another task or thread. In Mach, a message consists of a header and a variable-length body. Some system services are invoked by passing a message from a thread to the Mach port representing the task that provides the desired service. memory descriptor An object that describes how a stream of data, depending on direction, should either be laid into memory or extracted from memory. It represents a segment of memory holding the data involved in an I/O transfer and is specified as one or more physical or virtual address ranges. The object is derived from the IOMemoryDescriptor class. See also DMA, memory cursor message bubble In Xcode, a small window that displays a project message in place—that is, in the location the message applies to, such as a code line that contains an error. message digest The result of applying a cryptographic hash function to a message or other data. A cryptographically secure message digest memory-mapped file A file whose contents are mapped into memory. The virtual-memory system transfers portions of these contents from the file to 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 77 Glossary cannot be transformed back into the original message and cannot (or is very unlikely to) be created from a different input. Message digests are used to ensure that a message has not been corrupted or altered. For example, they are used for this purpose in digital signatures. The digital signature includes a digest of the original message, and the recipient prepares their own digest of the received message. If the two digests are identical, then the recipient can be confident that the message has not been altered or corrupted. to communicate with instrument unit audio units. MIDI data describes musical events, such as the starting or stopping of a note. Pronounced “MID-ee.” MIDI endpoint An abstract representation of a MIDI cable connection (or port) as used by Core MIDI. MIDI entity In Core MIDI, a logical grouping of MIDI endpoints. For example, a MIDI driver may group a MIDI-in and a MIDI-out endpoint together in a MIDI entity. MIDI port A one-way (send or receive) connection point in a hardware-based or virtual MIDI network. Each port can support up to 16 channels of MIDI data. In Core MIDI, a port is represented abstractly in software by a MIDI endpoint. See also MIDI. metamorphosis The process by which glyphs are rearranged, substituted, deleted, and inserted based upon their properties and contextual states. metapackage An installation package that contains other installation packages, usually component packages. Metapackages are used to deliver multicomponent products to users and to provide them with installation choices that allow them to choose which components to install. See also component package. MIDI timecode See MTC. MIG Mach interface generator. A language for generating RPC (remote procedure call) interfaces for interprocess communication between Mach tasks. MIME Multipurpose Internet Mail Extensions. A standard for transmitting formatted text, hypertext, graphics, and audio in email messages over the Internet. method In object-oriented programming, a procedure that can be executed by an object. microkernel A kernel implementing a minimal set of abstractions. Typically, higher-level OS services such as file systems and device drivers are implemented in layers above a microkernel, possibly in trusted user-mode servers. OS X is a hybrid between microkernel and monolithic kernel architectures. See also monolithic kernel. MIME type A string designating the type of data in an attachment transmitted via MIME, such as text/plain, image/jpeg, audio/mp3, or video/quicktime . MIME type hint Advisory metainformation suggesting the likely content type for a URL. In Search Kit, common MIME type hints include text/plain, text/rtf, text/html, text/pdf, and application/msword. middle reference form In AppleScript, the reference form that specifies the middle object of a particular class in a container. This form is rarely used. minimize button A window control (the middle yellow button that appears at the top left) that the user clicks to put a window into the Dock. MIDI Musical Instrument Digital Interface. A standard data protocol for communication between computers and electronic music instruments, first adopted in 1983 by the AES. Core Audio uses MIDI 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 78 Glossary minimum term frequency In Search Kit, the fewest number of times a term can appear in a document and still be indexed. This functionality is not currently supported by Search Kit indexes. the EOModeler application. A model also includes the information needed to connect to a particular database server. modeless dialog A dialog that does not require the user to dismiss it before interacting with anything else onscreen. The “find and replace” dialog in many word processors is an example of a modeless dialog. minimum term length In Search Kit, the shortest-length term to index. When Search Kit adds terms from a document to an index, it skips over words whose length is shorter than the minimum term length. model object In object-oriented programming, a type of object that contains the data of an application, provides access to that data, and implements logic to manipulate the data. mini system font The font used for the text in most mini controls. It is Lucida Grande Regular 9 pt. minor version A framework version specifier designating a framework that is compatible with programs linked with later builds of the framework within the same major version. Compare major version. Model-View-Controller See MVC. modelview matrix A 4 X 4 matrix used by OpenGL to transforms points, lines, polygons, and positions from object coordinates to eye coordinates. modifier key A key the user can hold down to alter the meaning of another key being pressed simultaneously or to alter the meaning of a mouse action. The Option and Command keys are examples of modifier keys. mipmaps In graphics, a set of texture maps, provided at various resolutions, whose purpose is to minimize artifacts that can occur when a texture is applied to a geometric primitive whose onscreen resolution doesn’t match the source texture map. Mipmapping derives from the latin phrase multum in parvo , which means “many things in a small place.” modifier track In QuickTime, a track in a movie that modifies the data or presentation of other tracks. For example, a tween track is a modifier track. See also tween track. missing character glyph The glyph in a font that is drawn when no glyph is defined for a character code in a font. Monitor WebObjects application used to administer deployed WebObjects applications. It’s capable of handling multiple applications, application instances, and applications hosts at the same time. mLAN Music local area network. A FireWire-based interconnection protocol that carries multichannel audio and MIDI over a single cable. See also MIDI. monolithic kernel A kernel architecture in which all pieces of the kernel are closely intertwined. A monolithic kernel provides substantial performance improvements. It is difficult to evolve the individual components independently, however. The OS X kernel is a hybrid of the monolithic and microkernel models. See also microkernel. model An object (of the EOModel class) that defines, in Entity-Relationship terms, the mapping between enterprise object classes and the database schema. This definition is typically stored in a file created with 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 79 Glossary monophonic Describes an instrument that plays only one note at a time. Compare polyphonic. See also monotimbral, multitimbral. movie display boundary region A region that describes the display area occupied by a movie in the display coordinate system, before the movie has been clipped by the movie display clipping region. See also movie display clipping region. monotimbral In Core Audio, describes an instrument unit configured to produce sounds of only a single timbre. Both monophonic and polyphonic instrument units can be monotimbral. Compare multitimbral. movie display clipping region The clipping region of a movie in the display coordinate system. Only that portion of the movie that lies in the clipping region is visible to the user. QuickTime applies the movie’s display clipping region to the movie display boundary region to obtain the visible image. See also movie display boundary region. mouse event coalescing A process that merges mouseMoved and mouseDragged events by checking to see if one of these events exists in the event queue, and if it does, updating the queue with the position and delta information from the more recently generated event. movie file A QuickTime file that stores a movie and its associated data. movie header atom A QT atom that specifies the characteristics of an entire QuickTime movie. movie A structure of time-based data that is managed by QuickTime. A movie may contain sound, video, animation, or a combination of any of these types of data. A QuickTime movie contains one or more tracks; each track represents a single data stream in the movie. See also time-based data, track. movie poster A single visual image representing a QuickTime movie. You specify a poster as a point in time in the movie and specify the tracks that are to be used to constitute the poster image. movie boundary region In QuickTime, a region that describes the area occupied by a movie in the movie coordinate system, before the movie has been clipped by the movie clipping region. A movie’s boundary region is built up from the track movie boundary regions for each of the movie’s tracks. See also movie clipping region, track movie boundary region. movie preview A short dynamic representation of a QuickTime movie. Movie previews typically last no more than 3 to 5 seconds, and they should give the user some idea of what the movie contains. You define a movie preview by specifying its start time, its duration, and its tracks. movie resource One of several data structures that provide the medium of exchange for movie data between applications on a Macintosh computer and between computers, even computers of different types. movie clipping region The clipping region of a movie in the movie’s coordinate system. QuickTime applies the movie’ slipping ’ region to the movie boundary region to obtain a clipped movie boundary region. Only that portion of the movie that lies in the clipped movie boundary region is then transformed into an image in the display coordinate system. See also movie boundary region. movie sprite A sprite that lives in a sprite track and acts in a movie. See also sprite track. Movie Toolbox Access Keys A QuickTime API that can be used to add password protection to QuickTime data. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 80 Glossary MP3 Common short form for MPEG-1, audio layer 3 . A lossy, perceptual compression format for audio data that can achieve 10:1 data compression with usable sound quality. MPEG-1 does not define a standard encoding algorithm for MP3; it specifies only the decoding algorithm, the bit stream (packet) format, and the file format. See also perceptual coding. the features introduced in MPEG-1 and MPEG-2 and adds features useful for streaming media and broadcast, among others. See also stream MPEG-4 AAC See AAC. MPEG-4 Part 14 See MP4. MTC MIDI timecode. A music synchronization protocol, defined as part of the MIDI protocol. MTC emulates SMPTE timecode. See also timecode. MP4 The MPEG-4 audio/video container format, also known as MPEG-4 Part 14. MP4 files can hold many different types of data, such as AAC and MP3 audio, or MPEG-2 and H.264 video. Typically, files with the.mp4 extension contain both audio and video data, while.m4a denotes files containing only audio data. multicast A process in which a single packet can be addressed to multiple recipients. Multicast is used, for example, in streaming video, in which many megabytes of data are sent over the network. multihoming The ability to have multiple network addresses in one computer, usually on different networks. For example, multihoming might be used to create a system in which one address is used to talk to hosts outside a firewall and the other to talk to hosts inside; the computer provides facilities for passing information between the two. MPEG Moving Picture Experts Group. An international working group of ISO/IEC that develops standards for digitally coded representations of audio and video. MPEG is part of the names of many perceptual coding formats published by the group. Pronounced “EM-peg.” See also IEC, ISO. multiplexing See interleaving. MPEG-1 A set of audio and video perceptual coding formats, formally designated as ISO/IEC-11172. MPEG-1 encompasses the Video CD and MP3 formats. multitasking The concurrent execution of multiple programs. OS X uses preemptive multitasking. multitimbral In Core Audio, describes an instrument unit configured to allow production of more than one timbre simultaneously. Compare monotimbral. MPEG-1, audio layer 3 See MP3. MPEG-2 A set of audio and video perceptual coding formats, formally designated as ISO/IEC-13818, first published in 1994. MPEG-2 encompasses formats of generally higher quality than MPEG-1, including broadcast-quality video and (with modifications) DVD movies. music One of the QuickTime media types, in which sequences of sounds and tones are generated. music player The Core Audio programming construct that applications use to play MIDI or other event data. MPEG-2 AAC See AAC. mutex lock A mutual-exclusion locking object that allows multiple threads to synchronize access to shared resources. A mutex has two states: locked and unlocked. Once a mutex has been locked by a MPEG-4 A set of audio and video perceptual coding formats, formally designated as ISO/IEC-14496, first published in 1998. MPEG-4 encompasses many of 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 81 Glossary thread, other threads attempting to lock it block. When the locking thread unlocks (releases) the mutex, one of the blocked threads (if any) acquires (locks) it and uses the resource. The thread that locks the mutex must be the one that unlocks it. The work-loop lock (which is used by a command gate) is based on a mutex. See also lock, work loop namespace An agreed-upon context in which names (identifiers) can be defined. Within a given namespace, all names must be unique. NAT Network address translation. A scheme that transforms network packets at a gateway so network addresses that are valid on one side of the gateway are translated into addresses that are valid on the other side. mutually exclusive attribute group A set of attribute choices in which the user can select only one item, such as font size. Compare accumulating attribute group. National Television System Committee See serif. native curve type The curve type—cubic or quadratic—used by a font designer to specify a font. MVC Model-View-Controller. A design pattern that assigns objects in an application to one of three roles and recommends a distinct separation among model, view, and controller objects. This is one of the central design patterns for Cocoa applications. navigation bar In Xcode, the bar along the top of the text editor that contains a number of controls that you can use to move between open files, jump to symbols, and open related files. name In Search Kit, a document name as represented in a document URL object. For documents that are on-disk files, the name should correspond to the actual filename. For other types of documents, your application can assign any name to a document. See also document URL object negative justification A layout in which the glyphs on a line do not naturally fit within the line width set by the developer. nested control statement In AppleScript, a control statement that is contained within another control statement. named region In Mach, a form of named memory entry that provides a form of memory sharing. NetInfo The network administrative information database and information retrieval system for OS X. Many OS X services consult the NetInfo database for their configuration information. name port In Mach, a port that allows access to nonprivileged operations against an object (for example, obtaining information about the object). In effect, it provides a name for the object without providing any significant access to the object. See also port, control port. network A group of hosts that can communicate with each other. network kernel extension See NKE. name reference form In AppleScript, a reference form that specifies an object by name—that is, by the value of its name property. NFS Network File System. The main file-sharing protocol used by UNIX systems. An NFS file server allows users on the network to share files on other hosts as if they were on their own local disks. named memory entry A handle (a port) to a mappable object backed by a memory manager. The object can be a region or a memory object. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 82 Glossary nib document The runtime representation of a nib file. Nib documents are the primary document type of the Interface Builder application. The on-disk representation of a nib document is a nib file. noise Undesired energy or data components in a communication channel included with the signal that the channel is carrying. See also noise floor, quantization noise. Compare distortion. nib file A special file created by Interface Builder that contains information required to create user interface objects (windows, controls, and menus). Nib files contain binary data representing resources that you load into your application at runtime. See also xib file. noise floor The amplitude of the noise in a communication channel when no signal is present, typically measured as a scalar, absolute level in decibels relative to a standard level such as using dBu. Noise can vary according to frequency, and perceived noise is subject to psychoacoustics, so the derivation of a single number to describe noise floor can entail weighting. Common weighting schemes are dBA, dBC, and unweighted. NKE Network kernel extension. A type of KEXT that provides a way to extend and modify the networking infrastructure of OS X dynamically without recompiling or relinking the kernel. noncontextual features Features that are applied in the same manner to a glyph regardless of the adjacent glyphs. Compare contextual features. NMI Nonmaskable interrupt. An interrupt produced by a particular keyboard sequence or button that cannot be blocked in software. It can be used to interrupt a hung system—for example to drop into a debugger. nonexclusive feature type A feature for which you can enable any number of feature selectors at once. Compare exclusive feature type. nobody A special user with very little access. To prevent someone running as root or as an administrator on one system from gaining control over another system through a network connection, such users are often mapped to the nobody user on the remote system. non-premultiplied In image processing, a technique for processing the alpha channel of a pixel. Instead of performing the alpha blend for each pixel, the alpha value is premultiplied to each of the other color channel values for that pixel. The pixel can then be interpreted as is from then on because all of the color channel values have been appropriately changed to reflect the alpha component. node (1) An audio unit in an audio processing graph. Each node has one or more inputs and outputs that must be connected to other audio units. See also head node. (2) A panorama or an object in a QuickTime VR movie. nonretained window A window without an offscreen buffer for screen pixel values. nonsimple message In Mach, a message that contains either a reference to a port or a pointer to data. Compare simple message. nodes file In Xcode, a file that describes the hierarchical structure of the documentation set. It defines the table of contents that users see in the browser view of the Xcode Documentation window and the relationships between entries in the documentation set hierarchy. nonzero winding number rule A fill rule that determines when to paint a pixel. The outcome depends on the direction that path segments are drawn. Compare with even-odd rule. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 83 Glossary notification A programmatic mechanism for alerting interested recipients (observers) that some event has occurred during program execution. The observers can be users, other processes, or even the same process that originates the notification. In OS X, the term is used to identify specific mechanisms that are variations of the basic meaning. In the kernel environment, notification is sometimes used to identify a message sent via IPC from kernel space to user space. Distributed notifications provide a way for a process to broadcast an alert (along with additional data) to any other process that makes itself an observer of that notification. Finally, the Notification Manager (a Carbon manager) lets background programs notify users—through blinking icons in the menu bar, by sounds, or by dialogs—that their intercession is required. In Enterprise Objects, it’s a mechanism that provides an asynchronous communication infrastructure between objects. nub An I/O Kit object that represents a detected, controllable entity such as a device or logical service. A nub may represent a bus, disk, graphics adaptor, or any number of similar entities. A nub supports dynamic configuration by providing a bridge between two drivers (and, by extension, between two families). A nub can also provide services to code running in user space through a device interface. See also device, driver number In AppleScript, a synonym for the classes integer and real . NURBS Non-uniform rational B-spline. A methodology use to specify parametric curves and surfaces. NVRAM Nonvolatile RAM. RAM storage that retains its state even when the power is off. See also RAM. Nyquist frequency The highest frequency signal that can be faithfully recorded for a given sampling rate. Attempts to sample a signal containing higher frequencies results in the generation of an alias signal below the Nyquist frequency. The Nyquist frequency is half the sampling rate. See also visual context. notify port A special Mach port that is part of a task. A task’s notify port receives messages from the kernel advising the task of changes in port access rights and of the status of messages it has sent. NSXMLOutputFormat WebObjects class that encapsulates format properties for an NSXMLOutputStream object. object (1) In object-oriented programming, a programming unit that groups together a data structure (fields) and the operations (methods) that can use or affect that data. Objects are the principal building blocks of object-oriented programs. (2) In Mach, a collection of data, with permissions and ownership. (3) In AppleScript, an instantiation of a class definition, which can include properties and actions. (4) A group of bright, high-intensity pixels in an image, as opposed to the darker pixels, which are considered part of the background. NSXMLOutputStream WebObjects class that serializes objects and data into XML documents. NTSC National Television System Committee. A color-encoding standard adopted by the committee in 1953. It was the first monochrome-compatible, simultaneous color transmission system used for public broadcasting. This method is used widely in the United States. object containment hierarchy In AppleScript, the hierarchy of objects in a running application. AppleScript and Cocoa scripting depend on the 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 84 Glossary object containment hierarchy to locate the objects on which to perform an operation. See also AppleScript object model. object specifier In AppleScript, a phrase that specifies the information needed to find another object in terms of the objects in which it is contained. Cocoa scripting makes use of object specifiers to find objects in your application while executing a script command and to return information requested by a script. See also absolute object specifier, object containment hierarchy, relative object specifier, reference form. object conversion See coercion. object file A file containing executable code and data. Object files in the Mach-O executable format take the suffix.oand are the product of compilation using the GNU compiler ( gcc ). Multiple object files are typically linked together along with required frameworks to create a program. See also code fragment, dynamic linking. object track A track in a QuickTime VR movie that contains a set of views of a VR object. object wrapper Code that defines an object-based interface for a set of procedural interfaces. Some Cocoa objects wrap Carbon interfaces to provide parallel functionality between Cocoa and Carbon applications. object-first command In AppleScript, a command that invokes a specified method of each specified receiver. With an object-first command, objects perform the specified action on themselves. Compare verb-first command. offset-binary encoding A method of digitally encoding sound that represents the range of amplitude values as an unsigned number, with the midpoint of the range representing silence. For example, an 8-bit sound sample stored in offset-binary format would contain sample values ranging from 0 to 255, with a value of 128 specifying silence (no amplitude). Samples in Macintosh sound resources are stored in offset-binary form. Compare twos-complement encoding. object graph In WebObjects, the graph of objects (especially enterprise object instances) that are contained by EOEditingContext objects. Objective-C An object-oriented programming language based on standard C and a runtime system that implements the dynamic functions of the language. The few Objective-C extensions to the C language are mostly based on Smalltalk, one of the first object-oriented programming languages. Objective-C is available in the Cocoa application environment. offsets Monotonically increasing or decreasing values. In ATSUI, offsets are in Unichars units and are typically used to specify starting and ending points for a string of text. object-relational mapping In WebObjects, a system for transforming Entity-Relationship models to an object-oriented programming framework. Enterprise Objects performs object-relational mapping (mapping database structures to Java objects) with the help of Entity-Relationship models called EOModels. See also Entity-Relationship modeling. Ogg A free collection of digital codecs for multimedia, including Ogg Vorbis for lossy compression of audio at medium-to-high bit rates, and Ogg FLAC for lossless audio. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 85 Glossary Ogg FLAC A free, open source, lossless audio codec. Ogg FLAC typically compresses CD audio by 50% with no data loss. FLAC is an acronym for Free Lossless Audio Codec . See also lossless compression. OpenGL Open Graphics Language. An industry-wide standard for developing portable 2D and 3D graphics applications. OpenGL consists of an API and libraries that developers use to render content in their applications. Ogg Vorbis A free, open source, lossy audio codec intended to compete with MP3. OpenGL buffer A buffer that holds image information in graphics card memory. In Core Video, you manipulate OpenGL buffers using the CVOpenGLBufferRef type, which is a wrapper around the standard OpenGL buffer type. OHCI Open Host Controller Interface. The register-level standards that are used by most USB and FireWire controller chips. one-shot timer A Carbon event timer that fires only once. See also event timer. OpenGL texture An immutable image that OpenGL uses to wrap onto primitives. In Core Video, you manipulate OpenGL textures using the CVOpenGLTextureRef type, which is a wrapper around the standard OpenGL texture type. one-time pad authentication A form of shared secret authentication in which both parties have an identical list of pairs of numbers, words, or symbols and each pair is used only once. Open Scripting Architecture See OSA. op code In the old Printing Manager, a value passed to a function that determines how the function should operate. These are not used in the Carbon Printing Manager. Accessor functions are used instead. open source Software that includes freely available access to source code, redistribution, modification, and derived works. The full definition is available athttp://www.opensource.org. Open Transport A legacy communications architecture for implementing network protocols and other communication features on computers running the Mac OS. Open Transport provides a set of programming interfaces that supports, among other things, both the AppleTalk and TCP/IP protocols. opaque type In Core Foundation and Carbon, an aggregate data type plus a suite of functions that operate on instances of that type. The individual fields of an initialized opaque type are hidden from clients, but the type’s functions offer access to most values of these fields. An opaque type is roughly equivalent to a class in object-oriented programming. operand An expression from which an operator derives a value. open To launch or activate an application or to present a document or URL for viewing or editing within an application. operation (1) In AppleScript, the evaluation of an expression that contains an operator. (2) In WebObjects, a specific process or task that a web service implements. Much like Java methods, a web service operation can define an arbitrary number of OpenCL Open Computing Language. A standards-based technology for performing general-purpose computations on a computer’s graphics processor. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 86 Glossary parameters and return values. Operations are invoked by web service consumers and executed by web service providers. OSA Open Scripting Architecture. A standard and extensible mechanism for interapplication communication in OS X. Implemented by a number of OS X frameworks and subframeworks, including the AE framework (which implements the Apple Event Manager) and the OpenScripting framework. Also includes the AppleScript component, which implements the AppleScript language. operation object An instance of the NSOperation class. Operation objects wrap the code and data associated with a task into an executable unit. operation queue An instance of the NSOperationQueue class. Operation queues manage the execution of operation objects. osacompile A shell tool for compiling script files. outlet A pointer to another object that can be set in Interface Builder. Applications use outlets to store references to objects in nib files. operator A symbol, word, or phrase that derives a value from another value or pair of values. In Search Kit, operators include AND , OR , NOT , parentheses, quotation marks, and several others. Search Kit interprets operators and determines the user’s intended search type according to the operators’ meanings. out-of-band Communication on a socket or interface that relates to the operation of the socket or interface rather than data destined for the endpoint (for example, ioctl and getsockopt calls). Compare in-band. optical alignment The fine adjustment of glyph positions at the ends of lines to give a more even visual appearance to margins. out-of-line data Data that is passed by reference in a Mach message, rather than being included in the message. Compare in-line data. optional parameter In AppleScript, a parameter that need not be included for a command to be successful. output audio queue See audio queue. Output Options pane A pane in the Print dialog that provides an option to save a print job as a file. order The maximum number of factors in an equation. For example, the equation x 2 + x + 1 has an order of 3 because there are three distinct factors output unit An audio unit of type 'auou'. Output units can start and stop the flow of audio data in the signal chain. Examples include the default output unit and the AUHAL. See also head node. in the equation ( x 2, x , and x 0). ordered tasks In Xcode, tasks that contain inputs that are the outputs of other tasks or outputs that are the inputs of other tasks. Compare unordered tasks. outside property A property in a script object that occurs outside of any handlers or nested script objects. Similarly, an outside variable or an outside statement occurs outside of handlers or nested script objects. Organizer action A predefined or custom task that Xcode performs on a directory. owner See UID. Organizer item In Xcode, a representation of a directory in the file system; these items are like symbolic links or folder references. pacing The distribution of the interpolated values of an animation across the duration of the animation. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 87 Glossary package (1) In OS X, a directory presented to the user so that it appears to be a single file, and whose contents are ordinarily inaccessible for browsing by the user. Compare folder. See also application packaging. (2) In Java, a way of storing, organizing, and categorizing related Java class files; typical package names are java.util and com.apple.cocoa.foundation. packet (1) In networking, an individual piece of information sent on a network. (2) In Core Audio, an encoding-defined unit of audio data comprising one or more frames. For PCM audio, each packet corresponds to one frame. For compressed audio, each packet corresponds to an encoding-defined number of uncompressed frames. For example, one packet of MPEG-2 AAC data decompresses to 1,024 frames of PCM data. Compare webpage template, uniquing. package identifier Identifies the package within the Installer package database. See also Installer package database. packet description In a variable-packet-size audio file or stream, metadata that specifies where a packet of audio data starts as well as its size. In Core Audio, a data structure used to represent a packet description in an audio data buffer. See also simple message, packet table. package list A pane in a PackageMaker project window that lists the packages the project defines. This list is divided in two parts: the installation-package file (which contains all the product’s files) and the subpackages or package references that contain components of the product. packet table In a variable-packet-size audio file or stream, metadata consisting of a table of packet descriptions. See also simple message, packet description. PackageMaker A tool that builds an installable software package from the files you provide. package properties Installer package data that provides Installer details about the package itself, such as its identifier, version number, and resource fork processing. packing Converting pixel color components from a buffer into the format needed by an application. page (1) (n.) The smallest unit (in bytes) of information that the virtual memory system can transfer between physical memory and backing store. (2) (v.) To transfer pages between physical memory and backing store. (3) (n.) In Quartz, the virtual canvas that Quartz paints to. package requirement A test that determines whether a package can be installed on the computer. A package requirement can be optional; such requirements display a warning to the user but allows the installation to proceed. Non-optional requirements prevent an installation from taking place. Page Attributes pane A pane in the Page Setup dialog that allows the user to set page format options—paper size, paper orientation, and scaling. package version number A positive integer that identifies an iteration of a single-component product package, or an iteration of a component package within a product package. This version number should be incremented when the contents or installation details of the package are changed. See also product package, component package. page format object An opaque data type used by the printing system to store information from the Page Setup dialog, such as paper size and orientation. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 88 Glossary page formatting A description of how the pages of a document should be printed; page formatting includes such information as page and paper sizes. palette A window that is independent of document windows and that provides items to be used when other windows are open, such as a palette that provides drawing tools. pager A module responsible for providing the data for the pages of a memory object. See also default pager, vnode pager. Palette window An Interface Builder window that provides a number of palettes (or panes), each of which contains object instances you can add to an application. page rectangle The rectangle marking the boundaries of the printable area on a page. The upper-left corner of the page rectangle always has the coordinates (0,0). The coordinates of the lower-right corner define the rectangle for the maximum imageable area attainable on the given printer; these coordinates are specified by the units used to express the resolution of the printing graphics port. pane An area of changeable content in a dialog or other window. Panes usually change as the result of the user clicking a button or choosing an item from a pop-up menu. In some cases, panes change as a process takes place, such as while the Installer application is running. panel A window that floats above other windows and provides tools or controls that users can work with while documents are open. Panel is not a user term; the equivalent term is window or dialog , as appropriate. See also document window. Page Setup dialog A dialog—usually displayed by an application in response to the user choosing the Page Setup command—that allows the user to specify the printing options (such as the paper size and the printing orientation) used by an application to format a document. panic An unrecoverable system failure explicitly triggered by the kernel with a call to panic. Compare kernel crash. pages view In Xcode, one of the three views provided by the all-in-one layout. panner unit In Core Audio, an audio unit of type 'aupn' that distributes a set of input channels, using a spatialization algorithm, to a set of output channels. In the simplest case, a panner unit places a monaural signal at a left/right spot in a stereo field. painter’s model In Quartz, a drawing model in which each successive drawing operation applies a layer of paint to a page. painting For the Quartz equivalent of the QuickDraw painting operation (such as that used for the QuickDraw function PaintOval), see filling. panning From panorama . In audio, the placement of a monaural signal within a stereo or multichannel (such as surround sound) sound field. Variations include stereo, SoundField, spherical head, vector, and HRTF panning. A more general term for panning is spatialization. PAL Phase Alternation Line. A color-encoding system used widely in Europe, in which one of the subcarrier phases derived from the color burst is inverted in phase from one line to the next. This technique minimizes hue errors that may result during color video transmission. Sometimes called Phase Alternating Line . panorama A structure of QuickTime VR data that forms a virtual-world environment within which the user can navigate. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 89 Glossary panorama track A track in a QuickTime VR movie that contains a panorama. parent object In AppleScript, an object from which another script object, called the child, inherits properties and handlers. A parent object may be any object, such as a list or an application object, but it is typically another script object. Paper Feed pane A pane in the Print dialog that lets the user specify the printer trays from which a print job should be printed. parser In computer science generally, a program that works with a tokenizer to interpret a sequence of tokens. In Audio File Stream Services, a software object of type AudioFileStreamID, used for reading audio file streams. paper rectangle The rectangle that describes the size of a piece of paper on which a page is printed. This rectangle is defined in the same coordinate system as the page rectangle. Thus, the upper-left coordinates of the paper rectangle are typically negative and its lower-right coordinates are greater than those of the page rectangle. partial string searching Matching of the terms in a query string to indexed terms, with implied wildcard characters at the start and end of each query term. Each term is matched separately. Search Kit does not currently support partial string searching as an option, but a client application can provide it by adding wildcard operators (asterisks) around each term before handing a query off to Search Kit. See also search. parameter In an audio unit, a variable that defines an adjustable attribute such as volume, pitch, or filter cutoff frequency. Each audio unit parameter has a name, a unit (such as Hertz or decibels), a default value and a value range, and an optional set of flags. In an audio queue, a parameter has only a value. Compare element, property, scope. passive driver A device driver that performs only basic power-management tasks, such as joining the power plane and changing the device’s power state. See also active driver. parameter variable In AppleScript, an identifier in a handler definition that represents the actual value of a parameter when the handler is called. Also called a formal parameter . pass-through mode A mode that does not modify data. With respect to keyboard-entry, pass-through mode allows users to enter ASCII characters in the context of a 2-byte script, without changing the keyboard script. parent atom A QT atom that contains other QT atoms, which are its child atoms. See also child atom. parent document URL object In Search Kit, for file-based documents, the location of the enclosing folder for a document or for another parent document URL object. Search Kit manages documents using parent-child relationships, not paths. You can construct the path of any document by following its parent document links. See also document URL object. password Data, usually a character string, used to authenticate a user for a service or application. pasteboard A standardized mechanism for exchanging data within applications or between applications. The most familiar use for pasteboards is handling copy and paste operations. The equivalent user term is Clipboard . 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 90 Glossary patch In Quartz Composer, the base processing unit in a composition, which executes and produces a result. Patches are similar to routines in traditional programming languages. See also macro patch. modulation, an analog signal is linearly encoded to a series of binary numbers by sampling an analog signal at regular intervals. See also encoding, linear, quantization. patch hierarchy In Quartz Composer, the levels in a composition created when macro patches are used. See also macro patch. PDF Portable document format. A file format created by Adobe Systems to represent documents in a manner independent of the software, hardware, and operating system. The format became an open standard in 2008. path (1) In Quartz, one or more shapes that Quartz paints as a unit. A path can consist of straight lines, curves, or both. It can be open or closed. (2) For documentation sets, the page to display when the user selects the documentation node or the folder containing that page. This path is interpreted relative to the base URL of the documentation node. peek To examine an event in an event queue (obtaining its class, kind, parameters and so on) without removing it from the queue. Compare pull. PEF Preferred Executable Format. The format of executable files used for applications and shared libraries in Mac OS 9; supported in OS X. The preferred format for OS X is Mach-O. pathname separator The “/” character that separates folder names in a raw pathname. A raw pathname should be displayed only to expert users or in a help tag. pen See stylus. pen event In the Ink Services technology, a mouse event that contains tablet data. pattern A sequence of drawing operations that Quartz can repeatedly paint to a graphics context. perceptual coding Lossy compression that takes advantage of limitations in human perception. In perceptual coding, audio data is selectively removed based on how unlikely it is that a listener will notice the removal. MP3 and MPEG-2 AAC are popular examples of perceptual coding. See also lossy compression. pattern space In Quartz, an abstract space that maps to the default user space by the transformation matrix (the pattern matrix) you specify when you create the pattern. Pattern space is separate from user space. The untransformed pattern space maps to the base (untransformed) user space, regardless of the state of the current transformation matrix. per-file compiler flags A flag that you can use to customize the build process of source files of a particular type. payload The product or product components contained in an installation package. See also installation package. permissions In BSD, a set of attributes governing who can read, write, and execute resources in the file system. The output of the ls -l command represents permissions as a nine-position code segmented into three binary three-character subcodes; the first subcode gives the permissions for the owner of the file, the second for the group pbuffer See simple search. PCM Pulse code modulation. A lossless encoding technique widely used for working with audio, invented by Alec H. Reeves in 1937. Sometimes called LPCM for linear pulse-code modulation , which distinguishes the process from ADPCM. In pulse-code 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 91 Glossary that the file belongs to, and the last for everyone else. The left-most position is reserved for a special character that says if this is a regular file (-), a directory (d), a symbolic link (l), or a special pseudo file device. The execute bit has a different semantic for directories, meaning they are searchable. See also ACL, authorization, UID. physical address An address to which a hardware device, such as a memory chip, can directly respond. Programs, including the Mach kernel, use virtual addresses that are translated to physical addresses by mapping hardware controlled by the Mach kernel. physical memory Electronic circuitry contained in random-access memory (RAM) chips, used to temporarily hold information at execution time. Addresses in a process’s virtual memory are mapped to addresses in physical memory. See also virtual memory personality A set of properties specifying the kinds of devices a driver can support. This information is stored in an XML matching dictionary defined in the information property list (Info.plist) file in the driver’s KEXT bundle. A single driver may present one or more personalities for matching; each personality specifies a class to instantiate. Such instances are passed a reference to the personality dictionary at initialization. picture comment A command or data used for special processing by output devices, such as printer drivers. Picture comments are usually stored in the definition of a picture or are included in the drawing an application does when printing. Pet Store A sample J2EE application from Sun Microsystems, which showcases the power and flexibility of the J2EE platform. picture taker panel The Image Kit picture taker class (IKPictureTaker ) that allows users to choose images by browsing the file system or by taking a snapshot with an iSight or other digital camera. The user term is picture taker . Phase Alternation Line See unidirectional text. phoneme A distinct unit that serves to distinguish between meanings of words. PID Process identifier. A number that uniquely identifies a process. Also called a process ID . phoneme modifier A symbol defined to adjust the pronunciation of an individual phoneme. Phoneme modifiers are also called prosodic control symbols . PIO Programmed input/output. A way to move data between a device and system memory in which each byte is transferred under control of the host processor. See also DMA. phrase searching Matching of a query string to indexed terms, with the query string considered as a complete phrase. A match occurs when the exact query phrase appears in a document. Search Kit supports phrase searching in inverted and inverted-vector indexes. See also search. pitch In psychoacoustics, a perceptual sound attribute that is roughly correlated with frequency. In general, pitch increases as the perceptually-dominant sound frequency increases. The strength of a pitch sensation depends on the sound character; noise-like sounds cause a weak pitch sensation, while pure tones evoke a strong pitch sensation. phrase termination Defines when Ink input should be processed by the recognizer. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 92 Glossary pitch modulation The maximum amount by which the actual frequency of speech may deviate from the speech pitch. placard A control that displays information. Typically placards are used in document windows as a way to quickly modify the view of the contents—for example, to change the current page or the magnification. pixel A picture element; the smallest element that the graphics hardware can display on the screen. In OpenGL, pixel is made up of all the bits at the location x , y , in all the bitplanes in the framebuffer. plaintext Ordinary, unencrypted data. Compare ciphertext. pixel buffer In general, a buffer that holds image information in main memory. In OpenGL, a type of drawable object that allows the use of offscreen buffers as sources for texturing. Pixel buffers allow hardware-accelerated rendering to a texture. planar image format A format that encodes a color channel for images. Planar images tend to be faster to operate on than nonplanar images because operations do not need to be repeated for each color channel. A grayscale image is an example of a planar image because it encodes only one (black and white) channel. pixel depth The number of bits per pixel in a pixel image. plane A subset of driver (or service) objects in the I/O Registry that have a certain type of provider/client relationship connecting them. The most general plane is the Service plane, which displays the objects in the same hierarchy in which they are attached during Registry construction. There are also the Audio, Power, Device Tree, FireWire, and USB planes. pixel format A format used to store pixel data in memory. The format describes the pixel components (that is, red, blue, green, alpha), the number and order of components, and other relevant information, such as whether a pixel contains stencil and depth values. pixel manipulation The process of operating on bits. Quartz does not provide functions that operate on a pixel-by-pixel basis. Core Image provides support for image processing on a per-pixel basis. Platform Expert A driver object for a particular motherboard that knows the type of platform the system is running on. The Platform Expert serves as the root of the I/O Registry tree. .pkg file An OS X Installer file. .pkg files can be combined into a metapackage (.mpkg). play state One of four states that a DVD can be in during playback: playing at a normal rate, paused, scanning forward, or scanning backward. PKI Public key infrastructure. As defined by the X.509 standard, the set of hardware, software, people, policies, and procedures needed to create, manage, store, distribute, and revoke digital certificates that are based on public key cryptography. PKI provides key management, data integrity, and data confidentiality. playback audio queue See audio queue. playback quality A relative measure of the fidelity of a track in a QuickTime movie. You can control the playback quality of a movie during movie playback. QuickTime chooses tracks from alternate tracks that most closely correspond to the display quality desired. See also alternate track. PKINIT A protocol that defines the use of public key cryptography for initial authentication in Kerberos. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 93 Glossary player See music player. polyphonic Describes an instrument capable of playing more than one note simultaneously. Compare monophonic. See also monotimbral, multitimbral. plist See property list. plug-in An external module of code and data separate from a host (such as an application, operating system, or other plug-in) that, by conforming to an interface defined by the host, can add features to the host without needing access to the source code of the host. Plug-ins are types of dynamically loadable bundles. They are implemented using the Core Foundation opaque type CFPlugin. pool See buffer pool. pop-up menu A menu that, when closed, displays the current choice and can be opened to present a list of mutually exclusive choices in a dialog or window. Pop-up menus have a double triangle indicator. pmap Part of Mach VM that provides an abstract way to set and fetch virtual-to-physical mappings from hardware. The pmap system is the machine-dependent layer of the VM system. port (1) In Mach, a secure unidirectional channel for communication between tasks running on a single system. (2) In IP transport protocols, an integer identifier used to select a receiver for an incoming packet or to specify the sender of an outgoing packet. (3) In Quartz Composer, the mechanism by which patches communicate. Ports can represent input or output parameters. Connections between input and output ports of different patches establish a data flow in a composition. See also MIDI port. point size The size of a font’s glyphs as measured from the baseline of one line of text to the baseline of the next line of single-spaced text. In the United States, point size is measured in typographic points. pointer (1) In programming, a data type whose value actually serves as a reference to a value stored in a specific location. (2) In a human interface, a cursor. port name In Mach, an integer index into a port namespace; a port right is specified with respect to its port name. See also port right. policy-based system A system that requires authorization to perform a privileged operations. port right In Mach, a specification of which task can send to or receive from a particular port. policy database A database containing the set of rules the Security Server uses to determine authorization. port right name A small integer used to identify a Mach port right. Each process has a port right namespace, which maps port right names to their corresponding port rights. A port right name is meaningful only within that task’s port right namespace. polynomial function In image processing, an equation commonly used for transforming pixel intensities in an image that is a summation of n factors and coefficients in the form of ax –1 + ... cx n + bx n port set In Mach, a set of zero or more Mach ports. A thread can receive messages sent to any of the ports contained in a port set by specifying the port set as a parameter to msg_receive(). 0. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 94 Glossary positional parameter In AppleScript, a handler parameter that is identified by the order in which it is listed. In a handler call, positional parameters are enclosed in parentheses and separated by commas. They must be listed in the order in which they appear in the corresponding handler definition. preauthorization A form of authorization used before performing the actual authorization. Preauthorization is used to determine if a user has the possibility of authorizing later. prebinding A process that Xcode applies when a program is built, by which the static linker replaces references to external symbols with the addresses of the symbols in the referenced libraries or tells the dynamic linker to resolve the references when a program is loaded or when a symbol is referenced. POSIX Portable Operating System Interface. An operating-system interface standardization effort supported by ISO/IEC, IEEE, and The Open Group. postcompensation action In text layout, the extra processing, such as addition of kashidas and ligature decomposition, that occurs after glyphs have been repositioned during justification. preemption The act of interrupting a currently running program in order to give time to another task. poster A frame shot from a movie, used to represent its content to the user. preemptive multitasking A type of multitasking in which the operating system can interrupt a currently running program in order to run another program, as needed. Compare cooperative multitasking. PostScript A language that describes the appearance (text and graphics) of a printed page. PostScript is an industry standard for printing and imaging. Many printers contain or can be loaded with PostScript software. PostScript handles industry-standard, scalable typefaces in the Type 1 and TrueType formats. PostScript is an output format of Quartz. preferred application The application selected by Launch Services in which to open a given document or URL, either through an explicit binding preference set by the user or, in the absence of such a user preference, by applying the implicit binding rules of Launch Services for determining the item’s default application. power child In the power plane, a driver for a device that relies on another object for its power. Compare power parent. See also plane. preferred rate The default playback rate for a QuickTime movie. power parent In the power plane, an object that provides power for a device. Compare power child. See also plane. preferred volume The default sound volume for a QuickTime movie. prefetching A feature in Enterprise Object that allows you to suppress fault creation for an entity’s relationships. Instead of creating faults, the relationship data is fetched when the entity is first fetched. See also faulting. PPD file PostScript printer description file. A text file, created by a printer vendor, that contains keywords and other information to specify features, options, and settings for a specific printer. prefix searching A specialized type of substring search. A prefix search involves matching a term in a query string to indexed terms, with an explicit 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 95 Glossary wildcard character at the end of the query term. A match occurs when the characters in the query term (minus the wildcard character) match the beginning of an indexed term. For example, the query string car* will match car, carpet, and carnivore. Search Kit supports prefix searching in inverted and inverted-vector indexes. See also search, substring searching, wildcard character. priming Adding leading frames or trailing frames to a set of audio data to support format conversion or SRC (sample rate conversion). If a converter requires priming and no leading or trailing frames are available, silent priming frames are typically used. See also priming frame. priming frame A webpage template of audio data used for priming. premultiplied In image processing, said of a pixel that already has its intensity levels appropriately multiplied by the alpha value. primitives The simplest elements in OpenGL—points, lines, polygons, bitmaps, and images. premultiplied alpha A source color whose components are already multiplied by an alpha value. Premultiplying speeds up the rendering of an image by eliminating an extra multiplication operation per color component. See also alpha. Print Center An application that allows users to locate and select printers, and control and obtain status for print jobs. Print dialog A dialog—usually displayed by an application in response to the user choosing the Print command—that solicits printing information from the user, such as the number of copies to print and the range of pages to print. preset A predefined set of parameter values for an audio unit. preview A short, potentially dynamic, visual representation of the contents of a file. Previews in file dialog boxes give the user a visual cue about a file’s contents. See also file preview. printer browser A module used to discover specific types of printers, such as USB or LPR printers. Printer Features pane A pane in the Print dialog that contains any user interface feature specified in a PostScript printer description (PPD) file that isn’t already a feature in Apple-provided panes or a developer’s custom pane. preview atom An atom of type 'pnot', which can appear in a QuickTime file to contain a movie’s file preview. primary key In relational databases, an attribute in an entity that uniquely identifies rows of that entity. For example, the Employee entity can contain an empID attribute that uniquely identifies each employee. printer module A printing plug-in that renders the graphics content in a print job for output to a specific model or family of printers. Printer modules are created by printer vendors to support a particular printer or printer family. primary line direction The dominant line direction (right-to-left or left-to-right) of the current text. The primary line direction is typically specified by the value of the global system direction variable. See also line direction. printer queue A temporary holding area for print jobs waiting to be printed. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 96 Glossary printing dialog A window provided by the printing system to elicit a response from the user. See also Page Setup dialog, Print dialog. print settings Information that controls the execution of a print job on a specific printer; print settings include such information as the number of copies, number of pages per sheet, and print quality settings. printing dialog extension A printing plug-in that implements one or more panes in a printing dialog. print settings object An opaque data type used by the printing system to store information from the Print dialog, such as number of copies, number of pages per sheet, and print quality. Printing Manager A collection of system software routines that can be used by a Classic application to print from the Macintosh computer to any type of connected printer. This has been replaced by the Carbon Printing Manager. priority In scheduling, a number that indicates how likely a thread is to run. The higher the thread’s priority, the more likely the thread is to run. See also scheduling policy. printing plug-in A stand-alone code module—packaged as a Core Foundation plug-in—that adds functionality to the OS X printing system. private key A cryptographic key that must be kept secret. Whereas a pair of identical private keys can be used as symmetric keys, asymmetric keys consist of one private key and one public key. printing presets Printer-specific collections of settings for the Print dialog. Printing presets are provided by Apple or printer vendors to reduce the need for users to navigate to different panes in the Print dialog. Presets are defined for a specific printing task, such as printing a photo on glossy photo paper. private MLTE scrap Scrap used exclusively by MLTE. privileged operation An operation that requires special rights or permissions; for example, changing a locked system preference. printing session object An opaque data type used by the printing system to store information that’s needed by the page format and print settings objects, such as default page format and print settings values. probe A phase of active matching in which a candidate driver communicates with a device and verifies whether it can drive it. The driver’s probe member function is invoked to kick off this phase. The driver returns a probe score that reflects its ability to drive the device. See also driver matching. print job The drawing commands that describe a document and the settings that control printing the document and keep track of it once the job has been added to a printer’s queue. process The runtime instance of an application or program. A process has its own virtual memory space and system resources (including port rights) that are independent of those assigned to other programs. A process always contains at least one thread (the main thread) and may contain any number of additional threads. print loop The sequence of function calls that set up and execute the printing of a document in an application. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 97 Glossary process dispatch source A dispatch source used to handle process-related events. A process source calls your custom event handler in response to changes to the process you specify. product container A file that contains a packaged or unpackaged product. The two container types are disk image and ZIP archive. product directory The file-system directory that contains a project file, the project’s source code and resources, and the build directory. process GID The GID of a process. Each process has three group IDs: the real group ID (RGID), effective group ID (EGID), and saved group ID (SGID). The RGID is always inherited from the user or process who executes the process. The EGID is the first GID in the group list. The SGID is used by BSD to enable a privileged process to switch in and out of privileged mode. product package An installation package that contains all the components of a product. Product packages with multicomponent products contain or reference component packages. See also installation package. product package editor A pane in a PackageMaker project window that specifies packaging and installation information about a product. This pane is displayed when the product package is selected in the package list. process identifier See simple statement. processor In Quartz Composer, a patch that processes data at specified intervals or in response to changing input values. process UID The UID of a process. Each process has three user IDs: the real user ID (RUID), effective user ID (EUID), and saved user ID (SUID). The RUID is always inherited from the user or process that executes the process. The EUID is normally the same as the RUID but can differ in special circumstances. It is the EUID that BSD checks to determine permissions. The SUID is used by BSD to enable a privileged process to switch in and out of privileged mode. product reference In Xcode, a special type of file reference that refers to the build system output for a particular target. A product reference lets you view your target’s products in the Groups & Files list. profile atom An atom of type 'prfl', which summarizes the features of a movie or track. profile rendering mode In Quartz Composer, a view that displays an analysis of each rendered frame in a composition; the analysis can help you to optimize performance. product An application or framework produced by Xcode. program A combination of code and resources that can be run to perform some task. Programs need not have a graphical user interface, although graphical applications are also considered programs. product component A self-contained part of a product. A product can have one or more components. The OS X file system contains special locations for several types of components. For example, application binaries are placed in Application directories, plug-ins are housed in Plugin directories, fonts live in Fonts directories, and so on. programmatic socket filter A socket filter that is enabled only under program control by calling setsockopt on a specific socket. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 98 Glossary programmed I/O I/O in which the CPU accomplishes data transfer with explicit load and store instructions to device registers, rather than DMA, and without the use of interrupts. This data transfer is often done in a byte-by-byte, or word-by-word fashion. Also known as direct I/O or polled I/O . See also DMA. values that KVC can access: attributes, to-one relationships, and to-many relationships. (3) In a scripting definition file, a characteristic of a class that has a single value and is identified by a label. Synonymous with a key-value coding (KVC) attribute or to-one relationship. A window’s name property would be equivalent to a KVC attribute, while its document property would be equivalent to a KVC to-one relationship. (3) In Core Audio, a key-value pair that declares an attribute or behavior, such as audio data stream format or latency. Each property has an associated data type to hold its value. Properties are typically non-time-varying and not directly settable by the user. Compare parameter. (4) In Entity-Relationship modeling, an attribute or relationship. See also attribute, relationship Program Portal A restricted-access area of the iOS Dev Center that allows you to configure devices to test your iOS applications. progress indicator A control that lets the user know that a task is in progress. project configuration In Xcode, the set of development features, project attributes, and project and target build settings used in a project. property list A structured, textual representation of data, commonly stored in Extensible Markup Language (XML) format. Elements of a property list represent data of certain types, such as arrays, dictionaries, and strings. See also information property list. project file A file created by Xcode that organizes source code, resources, and settings used to build a product. Project Info window In Xcode, the Info window for viewing and editing information kept at the project level, such as general information, project build settings, project build configurations, and project comments. property reference form In AppleScript, a reference form that specifies a property of an application , record , or script object. projection matrix A matrix that OpenGL uses to transform points, lines, polygons, and positions from eye coordinates to clip coordinates. prosodic control symbol See phoneme modifier. prosody The rhythm, intonation, and lexical stress in speech. project root In Xcode, the directory at which source-control operations are rooted and that serves as the origin of a project hierarchy. By default, a project root is the project directory. protected memory See memory protection. protocol handler A network module that extracts data from input packets (giving the data to interested programs) and inserts data into output packets (giving the output packet to the appropriate network device driver). project window A window that displays and organizes the files that make up an Xcode project. property (1) A labeled container in which to store a value. Properties can specify characteristics of objects. (2) In KVC, any of the three kinds of object 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 99 Glossary protocol plumber A network kernel extension that routes data between an interface and a network protocol stack. proxy object In Interface Builder, a placeholder for an object that is specified at runtime. Proxy objects act as stand-ins for objects that are not available at design time. Instead, such objects are created by a running application and connected to the objects in a nib file when that nib file is loaded. Cocoa nib files use proxy objects to represent the owner of a nib file’s contents, the application object itself, and the first object to respond to events. protocol stack A layer of the kernel network architecture containing the core functionality for a protocol family such as TCP/IP. protosw structure A data structure containing function pointers and data associated with a protocol family. pseudorandom number A number generated by an algorithm that produces a series of numbers with no discernible pattern. It should be impossible or nearly impossible to deduce the algorithm from such a series. However, unlike a truly random number generator, a pseudorandom number generator always produces the same series if the algorithm is given the same starting value or values. prototype attribute A special type of attribute available in EOModeler to provide a template for creating attributes. provider (1) A driver object that provides services of some kind to its client. In a driver stack, the provider in a provider/client relationship is closer to the Platform Expert. See also client. (2) In Quartz Composer, a patch that supplies data from an outside source to a composition. (3) In web services, an application that executes the logic that implements a web service operation. psychoacoustics The study of the perception of sound. The development of perceptual coding techniques relies on psychoacoustics. pthreads The POSIX threads implementation. See also WebObjects Builder, thread. provider identifier An identifier for the entity responsible for the contents of an installation package; for example,com.apple . PackageMaker uses this identifier to generate default package identifiers for a product package’s components. See also package identifier. public key A cryptographic key that can be shared or made public without compromising the cryptographic method. See also public key cryptography. public key certificate See digital certificate. provisioning profile A file that allows applications in development to be installed on an iOS-based device. It contains one or more development certificates, an application ID, and one or more device IDs public key cryptography A cryptographic method using asymmetric keys in which one key is made public while the other (the private key ) is kept secure. Data encrypted with one key must be decrypted with the other. If the public key is used to encrypt the data, only the holder of the private key can decrypt it; therefore the data is secure from unauthorized use. If the private key is used to encrypt the data, anyone with the public key can decrypt it. Because only the holder of the private proxy icon An icon in the title bar of a document window that users can manipulate as if they were manipulating the corresponding file-system object. Users can Command-click the proxy icon to display a pop-up menu illustrating the document path. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 100 Glossary key could have encrypted it, however, such data can be used for authentication. See also digital certificate, digital signature. which determines the dynamic range that can be represented, and a scaling factor, which determines the ratio between the analog and digital scales. public key infrastructure See PKI. quantization error The difference between an original analog signal value and its quantized digital representation. Quantization can sometimes results in a signal-correlated noise called quantization noise. See also dither. pull In Core Audio, to request and receive audio data, typically from a buffer. Data typically moves through an audio processing graph by way of a cascade of pull requests initiated by the head node. The head node pulls, and each object upstream passes on the pull until the cascade reaches an audio data source. quantization noise Signal-correlated noise resulting from rounding errors when quantizing a series of data samples. Application of a dither signal during analog-to-digital conversion can decorrelate quantization noise from the signal. The perceptual result is low-amplitude noise instead of distortion. pulse-code modulation See PCM. push button A rounded rectangle with a text label on it, which the user clicks to perform an instantaneous action, such as saving a document, completing operations defined by a dialog, or acknowledging an error message. quantum The fixed amount of time a thread or process can run before being preempted. quantum computer A computer in which the logic gates are based on quantum phenomena such as electron spin rather than mechanical or conventional electronic components. Because of the superposition of quantum states (a consequence of the Heisenberg Uncertainty Principle), a properly designed quantum computer can in principle perform simultaneously certain types of calculations that require a huge number of sequential operations in a classic computer. Consequently, factoring large numbers should be several orders of magnitude faster on a quantum computer than on present-day supercomputers. Because the strength of most modern cryptographic methods depends on the difficulty of making such calculations, a practical quantum computer would break most cryptographic schemes in common use. Although small proof-of-concept quantum computers have been constructed, no such machine capable of solving practical problems has yet been demonstrated. QCPlugIn A class defined by the Quartz framework that provides the base class to subclass for writing custom patches. QT atom A QuickTime atom that contains other atoms, possibly including other QT atoms and classic atoms. A data reference atom is an example of a QT atom. Compare classic atom. QTMA QuickTime Music Architecture. The part of QuickTime that lets other code create and manipulate music tracks in movies. QTVR track A track in a QuickTime movie that maintains a list of VR nodes. quadratic curve A curve specified by a quadratic equation. quantization The process of representing an analog (continuous-scale) value by a digital (discrete-scale) value. Quantization is characterized by a bit depth, 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 101 Glossary Quartz The native 2D rendering API for OS X. Quartz contains programmatic interfaces that provide high-quality graphics, compositing, translucency, and other effects for rendered content. Quartz is included as part of the Application Services umbrella framework. QuickDraw The original Mac OS two-dimensional drawing software, used by QuickTime. Quick Look framework A framework that provides a plug-in architecture for custom document types. A Quick Look document type can be displayed as a preview in the Finder and as an item in such applications as iPhoto or any application that supports slideshows created with the IKSlideshow class. Quartz Compositor An advanced windowing system that manages the onscreen presentation of Quartz, OpenGL, and QuickTime content, much as a video mixer does. QuickTime Apple’s multimedia authoring and rendering technology, implemented as a set of Macintosh system extensions or a Windows dynamic-link library that other code can use to create and manipulate time-based data. Quartz Extreme A technology integrated into the lower layers of Quartz that enables many graphics operations to be offloaded to hardware. This offloading of work to the graphics processing unit (GPU) provides tremendous acceleration for graphics-intensive applications. This technology is enabled automatically by Quartz and OpenGL on supported hardware. QuickTime VR A QuickTime media type that lets users interactively explore and examine photorealistic three-dimensional virtual worlds. QuickTime VR data structures are also called panoramas . query (n.) A text string, containing terms and operators, that represents a user’s information retrieval request. Various types of query supported by Search Kit include simple, prefix/suffix/substring, Boolean, phrase, and similarity. (v.) To invoke a request for information in an information retrieval system. See also search. radial gradient A fill that varies radially along an axis between two defined ends, which typically are both circles. Points share the same color value if they lie on the circumference of a circle whose center point falls on the axis. The radius of the circular sections of the gradient are defined by the radii of the end circles; the radius of each intermediate circle varies linearly from one end to the other. queue A queue is a JMS construct that allows for point-to-point messaging between applications. A message sent to a queue can be received by only one application. When several applications are subscribed to the queue, the messages are load balanced between the subscribers. radio button A control for one of a set of mutually exclusive, but related, choices. RAM Random-access memory. Memory that a microprocessor can either read or write to. queue-synchronized state The state of an input device according to the events that have been dispatched from the event queue. This state may differ from the actual physical state of the input device. Randomization Services AniOS API that produces cryptographically secure pseudorandom numbers. range reference form In AppleScript, a reference form that specifies a series of objects of the same class in the same container. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 102 Glossary ranked searching See relevance-based result. raw row fetching In WebObjects, a possible option in a fetch specification that retrieves database rows without forming enterprise objects from those rows. raster graphics Digital images created or captured (for example, by scanning a photo) as a set of samples of a given space. A raster is a grid of x-axis (horizontal) and y-axis (vertical) coordinates on a display space. (Three-dimensional images also have a z-coordinate.) A raster image identifies the monochrome or color value with which to illuminate each of these coordinates. The raster image is sometimes referred to as a bitmap because it contains information that is directly mapped to the display grid. A raster image is usually difficult to modify without loss of information. Examples of raster-image file types are BMP, TIFF, GIF, and JPEG files. See also vector graphics. real number A number that can include a decimal fraction. real position The actual drawing position on the x-axis for the origin of each character or glyph in a line of text given in coordinates relative to the preceding character or glyph. real time In reference to operating systems, a guarantee of a certain capability within a specified time constraint, thus permitting predictable, time-critical behavior. If the user defines or initiates an event and the event occurs instantaneously, the computer is said to be operating in real time. Real-time support is especially important for multimedia applications. rasterization In image processing, the process of converting vertex and pixel data to fragments, each of which corresponds to a pixel in the framebuffer. real-time performance Performance characterized by guaranteed worst-case response times. rate In QuickTime, a value that specifies the pace at which time passes for a time base. A time base’s rate is multiplied by the time scale to obtain the number of time units that pass per second. For example, consider a time base that operates in a time coordinate system that has a time scale of 60. If that time base has a rate of 1, 60 time units are processed per second. If the rate is set to 1/2, 30 time units pass per second. If the rate is 2, 120 time units pass per second. See also time base, time unit. realm In security, a subset of a large network served by its own Kerberos authentication server and ticket-granting server. receiver The object in an application designated to receive an AppleScript command. receive rights In Mach, the ability to receive messages on a Mach port. Only one task at a time can have receive rights for any one port. Compare send rights. rating indicator A control that displays a number of stars that indicates the relative ranking of an object (such as a song) based on a criterion such as popularity. receivers specifier In a script command object, the object specifier that specifies the objects in the application that should receive an command. raw format In AppleScript, terms enclosed in double angle brackets («, »). AppleScript uses raw format when it cannot find a script term in any available dictionary, or cannot display data in its native format. recognized text In Ink Services, Ink words processed by the recognition system. recognizer The algorithmic component of Ink Services that identifies written text and gestures. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 103 Glossary record (1) In databases in general, the set of values that describes a single instance of an entity. (2) In AppleScript, an unordered collection of properties, identified by unique labels. reference distance In Core Audio, for a panner unit, a parameter that specifies the real or apparent distance of an audio source from the listener beyond which the source’s level attenuates. recordable application In AppleScript, an application that uses Apple events to report user actions for recording purposes. When recording is turned on, Script Editor creates statements corresponding to any significant actions you perform in a recordable application. reference form In AppleScript, the syntax for identifying an object or group of objects in an application or other container—that is, the syntax for constructing an object specifier. AppleScript defines reference forms for arbitrary, every, filter, ID, index, middle, name, property, range, and relative. recording audio queue See audio queue. referential integrity In relational databases, the rules governing the consistency of relationships. recursive handler A handler that calls itself. reflexive relationship In relational databases, a relationship within the same entity; the relationship’s source join attribute and destination join attribute are in the same entity. recursive lock A lock that can be locked multiple times by the same thread. reentrant Said of code that can process multiple interleaved requests for service nearly simultaneously. For example, a reentrant function can begin responding to one call, be interrupted by other calls, and complete them all with the same results as if the function had received and executed each call serially. region code A code identifying one of the world regions for restricting DVD-Video playback. The world has been divided into eight separate regions to accommodate the varying release patterns of movies by the major studios. Therefore, each DVD player is compatible with a certain region: Region 1 for the United States and Canada, for example, and Region 2 for Japan and Europe. A DVD designated Region 0 can be played on any player regardless of its nationality. refactoring The process of modifying source code for the purpose of improving its readability and maintainability while retaining the program’s functionality and behavior. See also transformation. region of interest See Security Server. reference In AppleScript, the part of a script statement that identifies an object. Constructions such as first rectangle and document "My Notes" are references. Cocoa scripting provides built-in support for standard AppleScript reference forms. register To make an application known to Launch Services, copying its binding information into the Launch Services database and making it available for opening documents and URLs. relational database A database designed according to the relational model, which uses the discipline of Entity-Relationship modeling and the data design standards called normal forms. reference constant An arbitrary data item available for use by a program to convey information for its own purposes in an operation or data structure. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 104 Glossary relationship In relational databases, a link between two entities that’s based on attributes of the entities. For example, the Department and Employee entities can have a relationship based on the deptID attribute as a foreign key in Employee, and as the primary key in Department. This relationship would make it possible to find the employees for a given department. relevance-based search A ranked search whose result includes a relevance rating for each document matching a query. In general, relevance ratings may be normalized to 100%, or nonnormalized. Search Kit supports only nonnormalized results. See also inclusion/exclusion searching, search. relevance indicator A control that indicates the relative ranking of search results—the longer the bar, the more relevant the item is to the search criteria. relationship key In relational databases, a key (an attribute) on which a relationship joins. relocatable component A product component, such as an application binary or a plug-in, that the user may move after it has been installed. relative object specifier In AppleScript, an object specifier that does not include enough information to identify an object or objects uniquely. When AppleScript encounters a partial object specifier, it uses the default object specified in the enclosing tell statement to complete the reference. Compare absolute object specifier. relocation The ability of users to change the installation location of a package before an installation. remote install A network administrator–driven installation process. An administrator uses Apple Remote Desktop to install a package onto a set of client computers. relative position A position for the origin of each character or glyph in a line of text given in coordinates relative to the preceding character or glyph. Compare absolute position. remote procedure call See RPC. relative reference form In AppleScript, a reference form that specifies an object or location by describing its position in relation to another object, known as the base , in the same container. render In Core Audio, to apply a recipe or specification for signal processing to some audio data. An audio unit typically contains a rendering method to obtain audio data and perform processing. release A decrementing of the reference count of an object. When an object’s reference count reaches zero, it is freed. When your code no longer needs to reference a retained object, it should release it. Some APIs automatically execute a release on the caller’s behalf, particularly in cases where the object in question is being “handed off.” Retains and releases must be carefully balanced; too many releases can cause panics and other unexpected failures due to accesses of freed memory. See also retain. renderbuffer In OpenGL, a rendering destination for a 2D pixel image, used for generalized offscreen rendering, as defined in the OpenGL specification for the GL_EXT_framebuffer_object extension. renderer A combination of hardware and software, or software only, that OpenGL uses to create an image from a view and a model. The hardware portion of a renderer is associated with a particular display device and supports specific capabilities, such as the ability to support a certain color depth relevance-based result See relevance-based search. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 105 Glossary or buffering mode. A renderer that uses only software is called a software renderer and is typically used as a fallback. required events Certain Apple events that all Mac apps that present a graphical user interface should be able to respond to. These events can be sent by the Mac OS, as well as by other applications and by users executing scripts. They include the open application, open documents, print documents, open contents, reopen, and quit events. rendering context In OpenGL, a container for state information. rendering intent Specifies how Quartz maps colors from the source color space to those that are within the gamut of the destination color space of a graphics context. required parameter In AppleScript, a parameter that must be included for a command to be successful. rendering pipeline The order of operations used by OpenGL to transform pixel and vertex data to an image in the framebuffer. resampling (1) In audio, the process of taking samples of a digitized signal at a rate different from that of the original recording. Specific types of resampling include downsampling (resampling at a rate lower than the original) and upsampling (resampling at a higher rate). (2) In image processing, an operation that changes the dimensions of an image. render-to-texture In OpenGL, an operation that draws content directly to a texture target. repeat statement In AppleScript, a control statement that contains a series of statements to be repeated and, in most cases, instructions that specify when the repetition stops. resampling filter A function used to determine new pixel values for an image that has its dimensions changed somehow. reply port A Mach port associated with a thread that is used in remote procedure calls. repository A directory tree or database that contains the files managed by a source control system. Research Assistant A lightweight window that provides a condensed view of the API reference and links to related documentation for the selected system or build setting. repository configuration A set of data that tells Xcode how to use a particular source-control client tool to access a specific repository. reserved word A word that is part of the AppleScript language. request A message conforming to the Hypertext Transfer Protocol (HTTP) sent from the user’s web browser to a web server that asks for a resource such as a webpage. See also response. reset (1) For audio units, to return an audio unit to its just-initialized state. (2) For codecs, to clear the codec’s input buffer and return the codec to its just-initialized state. request-response loop The main loop of a WebObjects application, which receives a request, responds to it, and awaits the next request. resize control The area in the lower-right corner of windows that users can drag to adjust the size of the window. It is not present if the window’s contents cannot vary in size. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 106 Glossary resolution The number of pixels (individual points of color) contained on a display, expressed in terms of the number of pixels on the horizontal axis and the number on the vertical axis. The sharpness of the image on a display depends on the resolution and the size of the monitor. The same resolution will be sharper on a smaller monitor and gradually lose sharpness on larger monitors because the same number of pixels are being spread out over a larger area. Resolution is usually specified in dots per inch, or dpi, in the x and y directions. retain An incrementing of the reference count of an object. An object with a positive reference count is not freed. (A newly created object has a reference count of one.) Drivers can ensure the persistence of an object beyond the present scope by retaining it. Many APIs automatically execute a retain on the caller’s behalf, particularly APIs used to create or gain access to objects. Retains and releases must be carefully balanced; too many retains will result in wired memory leak. Compare release. retained window A window with an offscreen buffer for screen pixel values. Images are rendered into the buffer for any portions of the window that aren’t visible onscreen. resolution independence A feature that supports drawing to an abstract space such that drawing is the same size when rendered for raster devices of any native resolution. return statement In AppleScript, a statement that exits a handler and optionally returns a specified value. resource Anything used by executable code, especially by applications. Resources include images, sounds, icons, localized strings, archived user interface objects, and various other things. OS X supports both Resource Manager–style resources and “per-file” resources. Localized and nonlocalized resources are put in specific places within bundles. reusable component In WebObjects, a component that can be nested within other components and acts like a dynamic element. reverb See reverberation. resource fork The part of a file that historically held an application’s resources. Use of the resource fork is discouraged in OS X, but you can store resources in the data fork. reverberation An acoustic phenomenon produced by the cumulative addition of multiple sound reflections. Apple supplies the matrix reverb audio unit to simulate reverberation using DSP (digital signal processing). responder chain The set of objects responsible for handling events in a window. reverse multiplexing See deinterleaving. response In WebObjects, a message conforming to the Hypertext Transfer Protocol (HTTP) sent from the web server to the user’s web browser that contains the resource specified by the corresponding request. The response is typically a webpage. See also request. revision number A value that indicates a particular version of a project that’s been committed to the repository, also known as a version number . RGBA Red, green, blue, and alpha color components. RGID Real group ID. A group ID that is inherited from the user or process that executes a process. See also GID. result In AppleScript, a value generated when a command is executed or an expression evaluated. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 107 Glossary RIFF Resource Interchange File Format. A minor variation on IFF that uses little-endian integers. Roman baseline The baseline used in most Roman scripts and in Arabic and Hebrew. right In security, a named privilege. The Security Server authorizes rights for a user to perform a privileged operation. Roman character set A set of characters used for the Roman writing system. Roman character sets include the Standard Roman character set and the ASCII character set. right-side bearing The white space on the right side of the glyph; this value may or may not be equal to the value of the left-side bearing. Roman keyboard script A keyboard script that uses the Roman character set. RMS Root mean square. A statistical measure of a time-varying value, such as voltage, current, or sound pressure. An RMS value is derived as the square root of the mean of the squares of a series of values. In the case of a continuously varying value, it is derived from an integration of the transfer function. For the special case of a sine wave signal, the calculation simplifies to Vrms = 0.707 * Vpeak. May also be written in lowercase as rms . root (1) The user with unlimited system privileges. Also called the superuser . (2) The top directory in a BSD-style directory hierarchy. Written as a slash (/), it is the first element in every absolute pathname. root atom The largest atom container in a hierarchy, with atom type 'sean'. root certificate A certificate that can be verified without recourse to another certificate. Rather than being signed by a further certification authority (CA), a root certificate is verified using the widely available public key of the CA that issued the root certificate. Compare anchor certificate. ROI Region of interest. The portion of an image data buffer that is being operated upon by a function. It is not uncommon to allocate a large pixel buffer to hold several images and then process only the smaller ROIs when need be. root certification authority The owner of the root certificate. role (1) An identifier of an application’s relation to a document type. There are five roles: Editor (reads and modifies), Viewer (can only read), Print (can only print), Shell (provides runtime services), and None (declares information about type). You specify document roles in an application’s information property list. (2) In Xcode, the scope of the header file in a project: public, private, or project. root control An invisible control within which all other controls for window are embedded. root macro patch In Quartz Composer, the main routine in a composition; the evaluation of a composition begins at the root macro patch. All patches are nested, at one level or another, within the root macro patch. Ports that you publish at the root macro patch are accessible externally. role mask A parameter specifying the role or roles that an application should claim with respect to a given item in order to be considered a candidate for opening that item. root file system The primary file system off which a computer boots, so named because it includes the root node of the file-system tree. ROM Read-only memory. Memory that cannot be written to. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 108 Glossary root user The user on a UNIX system with a UID of 0. A process running with an EUID of 0 is said to be running as root . The root user owns many of the primary system processes and has unlimited access to the file system objects on the devices attached to the computer. Also called the superuser . RSS Really Simple Syndication. A lightweight XML format used for displaying changes frequently updated websites. root word See stem. ruby text Text usually used to provide annotations or indicate pronunciation for Asian languages. Ruby text is displayed using a smaller font size than the text it annotates. rotation In image processing, an operation that moves the coordinate space the specified angle. RUID Real user ID. The UID inherited from the user or process that executes a process. round button A circular push button. rule A set of attributes used to set security policies for applications and for the system. See also policy database. routine In Mach, a remote procedure call that returns a value. A routine can be used for synchronous or asynchronous operations. See also simpleroutine. run A sequence of glyphs that are contiguous in memory and share a set of common attributes. See also font run. row In a relational database, the dimension of a table that groups attributes into records. run loop The fundamental mechanism for event monitoring in OS X. A run loop registers input sources such as sockets, Mach ports, and pipes for a thread; it also enables the delivery of events through these sources. In addition to sources, run loops can also register timers and observers. There is exactly one run loop per thread. RPC Remote procedure call. An interface to IPC that appears (to the caller) as an ordinary function call. In Mach, RPCs are implemented using MIG-generated interface libraries and Mach messages. RSA encryption A system of public key cryptography, named for its inventors: Ron Rivest, Adi Shamir, and Leonard Adleman. The RSA algorithm takes two large prime numbers, finds their product, and then derives asymmetric keys from the prime numbers and their product. Because the public key includes the product, the private key could be derived from the public key if the product could be factored. No easy method for factoring products of large prime numbers is currently known, but it has not been mathematically proven that no such method is possible. Therefore, the discovery of a fast way to factor such numbers, or the development of quantum computers, would break RSA. run loop mode A collection of input sources, timer sources, and run loop observers associated with a particular name. When run in a specific mode, a run loop monitors only the sources and observers associated with that mode. run loop object An instance of the NSRunLoop class or CFRunLoopRef opaque type. These objects provide the interface for implementing an event-processing loop in a thread. run loop observer A recipient of notifications during various phases of a run loop’s execution. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 109 Glossary runtime The period of time during which a program is being executed, as opposed to compile time or load time. Can also refer to the runtime environment, which designates the set of conventions that arbitrate how software is generated into executable code, how code is mapped into memory, and how functions call one another. sample period The time span from one sample to the next. The inverse of sample rate. sample rate During playback, the number of samples played per second for each channel of an audio file. During recording, the number of samples acquired per second for each channel. Also called sampling rate . More properly, but less commonly, called sampling frequency . Compare frame rate. Safari The default web browser that ships with OS X. sample rate conversion See SRC. safety offset A property of an audio unit or other audio device that specifies a time lag, in samples, to allow for improved robustness of driver operation. The safety offset required for a given architecture includes time needed for memory access and to account for inaccuracies in a driver’s timestamp resolution. Safety offset contributes to latency. sampling frequency An alternate name for sample rate. sandboxing A system feature that provides fine-grained control of the ability of processes to access system resources, therefore limiting the amount of damage that can be done by a malicious hacker who gains control of an application. Samba Software that implements SMB/CIFS on a UNIX server. SBR Spectral Bandwidth Replication. A technique used in AAC (Advanced Audio Coding) encoding (among other encoding technologies) to improve perceived audio quality. sample (1) (n.) An instantaneous amplitude of the signal in a single audio channel, represented as an integer, floating-point, or fixed-point number. See also fixed-point sample. (2) (v.) To collect samples from an audio source, typically an analog audio source. Sampling typically involves collecting samples at regular, very brief intervals such as 1/44,100 seconds. (3) (n.) An excerpt of a longer recording. When the excerpt is intended to be played repeatedly, it is called a loop. (4) (v.) To record a sample to use as a loop or for inclusion in a another recording. (5) In QuickTime, a single element of a sequence of time-ordered data. scalar programming A programming paradigm in which values are operated upon individually. Scalar programming is more common than vector code. scale To shrink or enlarge an image by a certain percent. scaling An operation that changes the scale of the coordinate space by the specified x and y factors, effectively stretching or shrinking coordinates. The magnitude of the x and y factors governs whether the new coordinates are larger or smaller than the original. A negative factor flips the corresponding axis. sample format In QuickTime, the format of data samples in a track, such as a sprite track. sample number In QuickTime, a number that identifies the sample with data for a specified time. scan direction In DVD playback, a forward or backward direction with respect to the video stream. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 110 Glossary scan rate A constant used in DVD Playback Services to specify the speed of play. A scan rate of 1x represents the normal playback speed; other scan rates are multiples of the normal speed. by specific tools (such as CVS and Subversion), which manage the repository and handle check-ins and check-outs of code resources by engineers. scope (1) The availability of resources such as variables and objects within various parts of a program. In traditional procedural programming, scope is either global or local; however, scopes can be nested. (2) In AppleScript, the range over which AppleScript recognizes a variable or property, which determines where else in a script you may refer to that variable or property. (3) In Core Audio, a programmatic context within an audio unit. Unlike the general computer science notion of scopes, however, audio unit scopes cannot be nested. Each scope is a discrete context. You use scopes when writing code that sets or retrieves values of parameters or properties. Compare element. See also parameter, property. scene See chapter. scheduler The part of Mach that determines when each program (or program thread) runs, including assignment of start times. The priority of a program’s thread can affect its scheduling. See also task, thread. scheduling The determination of when each process or task runs, including assignment of start times. scheduling policy In Mach, how a thread’s priority is set and under what circumstances the thread runs. See also priority. schema A file that describes the structure of an XML document. This file can be a DTD file or an XML Schema file. screen metrics Resolution-dependent measurements used to describe how a glyph is drawn. Compare ideal metrics. scheme The component of a URL that identifies the type of resource it represents or the protocol to be used for accessing it, such as http, ftp, mailto, or file. See also document URL object. script (1) A series of statements, written in a scripting language such as AppleScript or Perl, that instruct an application or the operating system to perform various operations. Interpreter programs translate scripts. (2) A method for depicting words visually. Some examples of scripts are Latin, Greek, Hiragana, Katakana, and Han. scheme-definition dictionary A dictionary, specified in an application’s bundle information property list, that declares a particular URL type that the application claims to handle. Compare type-definition dictionary. scriptability information Information that formally lays out the AppleScript object model for an application and maps it to application objects. Scriptability information specifies the terminology available for use in scripts that target the application. It also provides information, used by AppleScript and by Cocoa, about how support for that terminology is implemented in the application. See also scripting definition format, script suite format. SCM Source control management. A set of tools and procedures developers can use for managing files and changes made to them over time. Also known simply as source control or as version control . SCM repository Source Code Management repository. A code database used to enable the collaborative development of large projects by multiple engineers. An SCM repository is managed 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 111 Glossary scriptable application An application that can be controlled by a script. For AppleScript, that means being responsive to interapplication messages, called Apple events, sent when a script command targets the application. scripting definition format An XML-based format that describes a set of scriptability terms and the commands, classes, constants, and other information used to support an application’s scriptability. Also called sdef format . Compare script suite format. script application An application whose only function is to run a script associated with it. script object A user-defined object, combining data (in the form of properties) and handlers, that can be used in a script. script command object An object that encapsulates all the information needed to perform an AppleScript command. Cocoa scripting creates script command objects in response to Apple events received by the application. A script command object is instantiated from NSScriptCommand or from one of its subclasses—either those provided by Cocoa scripting to handle standard AppleScript commands, or those defined by your application to perform its unique operations. script object definition A compound statement that can contain collections of properties, handlers, and other AppleScript script statements. script suite The combination of at least one suite definition and one suite terminology that together define the scripting capabilities and terminology for Cocoa applications. script suite file A property list file, in a specific format, that describes scriptable classes in terms of their attributes, relationships, and supported commands and that has the extension .scriptSuite. Script suite files, together with corresponding script terminology files, declare the scriptability information for a scriptable application. See also script terminology file. Script Editor An application distributed with OS X that provides a basic environment for editing, compiling, and executing scripts. scripting addition Code, stored in /System/Library/SystemAdditions, that makes additional commands or coercions available to scripts on the same computer. script suite format A format for providing scriptability information in the form of property list files, consisting of a script suite file together with a corresponding script terminology file. Compare scripting definition format. scripting addition command A command that is implemented as a scripting addition. scripting definition file A file in the scripting definition format that provides the scriptability information for an application. A scripting definition file has the extension .sdef and is also called an sdef file or simply an sdef . Compare script suite file, script terminology file. script system A collection of software utilities that provides for the representation of a specific writing system. It consists of a set of keyboard resources, a set of international resources, and one or more fonts. Script systems include Roman, Japanese, Arabic, traditional Chinese, Simplified Chinese, Hebrew, Greek, Thai, and Korean. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 112 Glossary script terminology file A property list file, in a specific format, that provides AppleScript terminology—the English-like words and phrases a scripter can use in a script—for the class and command descriptions in the corresponding script suite file. A script terminology file has the extension .scriptTerminology. Together with a corresponding script suite file, it declares the scriptability information for a scriptable application. See also script suite file. SCSI Architecture Model A specification, approved as ANSI standard X3.270-1996, that defines a common interface standard between computers and devices such as disk drives, printers, and scanners. sdef See scripting definition file. SDK Software Development Kit. A complete set of header files and stub libraries as shipped in a particular version of OS X. SDK family Group of SDK releases used to build software products for a particular Apple platform. The available SDK families are iPhone Device SDK, iOS Simulator SDK, and OS X SDK. scroll arrows Small buttons that appear on the scroll control that let the user incrementally advance the scrollers without dragging. search In an information retrieval system, a process that attempts to locate documents that match a query, and that may assign relevance scores to the found documents. Upon a successful match, a search system returns references to the found documents. Search Kit supports a variety of search types, some of which can be combined. These types are simple, Boolean, ranked, unranked, phrase, similarity, prefix, suffix, and substring. scroll bar A control for viewing areas of a document or a list that is larger than can fit in the current window. Only the active window can be scrolled. A window can have a horizontal scroll bar, a vertical scroll bar, both, or neither. scroller The part of a scroll bar that the user drags to view other parts of a document. The scroller size reflects how much of the document is visible; the smaller the scroller, the less of the content the user can see at that time. The scroller represents the relative location, in the whole document, of the portion that can be seen in the window. searchable Ink In Ink Services, Ink that remains visible to the user, but for which recognition has taken place. search field A text field with rounded corners used for searching. It can include a menu and an icon to clear the field or steps of a search. scrolling list A list in a dialog that uses scroll bars to reveal its contents. scrolling menu A menu that contains more items than are visible onscreen. Scrolling menus have triangles that indicate hidden menu items. search mode In Xcode, a mode that the Documentation window operates in. You can find documents by API symbol name, document title, or document content. Compare browse mode. SCSI Small Computer Systems Interface. A standard connector and communications protocol used for connecting devices such as disk drives to computers. search object In Search Kit, an opaque data type representing an asynchronous search and containing its results, accumulated as they are found. A search object is of type SKSearchRef. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 113 Glossary search result In Xcode, the set of documents that meet search criteria. Security Agent In OS X, a process used by the Security Server to communicate with the user through dialogs and other user interface elements. search strip In Xcode, a user interface element that appears below the Documentation window toolbar during a search. It allows you to choose a type of search. Security Objective-C API An OS X API providing a set of Objective-C methods that are wrappers for the Authentication Services functions plus a set of classes that display security-related UI elements. SECAM Systeme Electronique Couleur avec Memoire. A color-encoding system in which the red and blue color-difference information is transmitted on alternate lines, requiring a one-line memory in order to decode green information. Translated into English as Sequential Color with Memory . Security Server A daemon running in OS X and iOS that implements security protocols for such purposes as encryption, decryption, and authorization computation. The use of the Security Server to perform actions with cryptographic keys allows the keys to be maintained in a separate address space from the client application, keeping them more secure. In OS X, the Security Server uses a process called the Security Agent to communicate with the user through dialogs and other user interface elements. secret The encrypted data in a keychain item, such as a password. Only a trusted application can read the secret of a keychain item. Compare attribute. secret key A cryptographic key that cannot be made public without compromising the security of the cryptographic method. In symmetric key cryptography , the secret key is used both to encrypt and decrypt the data. In asymmetric key cryptography , the secret key is paired with a public key. Whichever one is used to encrypt the data, the other is used to decrypt it. See also public key, public key cryptography. seek To set an audio file or buffer’s read position to a specified webpage template. segmented control A control for changing modes or views; each segment represents a different state. selection range The contiguous sequence of characters in the source text that mark where the next editing operation is to occur. The glyphs corresponding to those characters are commonly highlighted onscreen. Secure Sockets Layer See SSL. secure storage Encrypted storage of data that requires a user or process to authenticate itself before the data is decrypted. Secure storage persists when the power is turned off. self-restricted application An application that restricts part of its features to specific users. Secure Transport The OS X and iOS implementation of SSL (Secure Transport Layer) and TLS, used to create secure connections over TCP/IP connections such as the Internet. On OS X, Secure Transport includes an API that is independent of the underlying transport protocol. The CFNetwork and URL Loading System APIs use the services of Secure Transport. semaphore A protected variable that restricts access to a shared resource. Semaphores are used to coordinate activities in which multiple processes compete for the same resources—for example, to share a common memory space or to share access to files. Mutexes and conditions are both types of 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 114 Glossary semaphore. A semaphore is similar to a lock, except that a finite number of threads can be holding a semaphore at the same time. See also lock. servlet A Java program that runs as part of a network service, typically a web server and responds to requests from clients. Servlets extend a web server by generating content dynamically. send rights In Mach, the ability to send messages to a Mach port. Many tasks can have send rights for the same port. Compare receive rights. servlet container A Java application that provides a working environment for servlets. It manages the servlet’s interaction with its client and provides the servlet access to various Java-based services. Containers can be implemented as standalone web servers, server plug-ins, and components that can be embedded in an application. separator A line used to break a window into visual regions. sequence In Core Audio, a collection of tracks to be played by a music player. A sequence always contains one or more event tracks and a tempo track. See also event track. sequencer Software or hardware for recording, playback, and editing of MIDI data or audio samples (excerpts or loops). See also SGML, MIDI. session A period during which access to a WebObjects application and its resources is granted to a particular client (typically a browser). Also an object (of the WOSession class) representing a session. serif The fine lines stemming from and at an angle to the upper and lower ends of the main strokes of a letter—for example, the little “feet” on the bottom of the vertical strokes in the uppercase letter “M” in Times Roman typeface. session key A cryptographic key calculated or issued for use only for the duration of a specific communication session. Session keys are used, for example, by the Diffie-Hellman key exchange and Kerberos protocols. server (1) A process that provides services to other processes (clients) in the same or other computers. In source control, a server is the process that modifies the repository. (2) A computer running OS X Server. setter In refactoring code, the method to use to set the value of the transformation item. setuid bit The fourth bit in a resource’s permissions code. When this bit is set to s , the system allows the process running it to masquerade as another user. For example, -r-sr-xr-x 1 root wheel traceroute allows the process running the traceroute utility to run as root. service A service is an I/O Kit entity, based on a subclass of IOService, that has been published with the registerService method and provides certain capabilities to other I/O Kit objects. In the I/O Kit’s layered architecture, each layer is a client of the layer below it and a provider of services to the layer above it. A service type is identified by a matching dictionary that describes properties of the service. A nub or driver can provide services to other I/O Kit objects. setuid tool A tool that has its setuid bit set. setup assistant A small application that guides users through the setup options for a hardware device or software component. SGID Saved group ID. The GID used by BSD to enable a privileged process to switch in and out of privileged mode. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 115 Glossary SGML Standard Generalized Markup Language. A language that allows the creation of sharable documents with a formal type and element structure. shell An interactive programming language interpreter that runs in a Terminal window. OS X includes several shells, each with a specialized syntax for executing commands and writing structured programs, called shell scripts . shader In image processing, a program that computes surface properties. Shift-click To click while the Shift key is down. This combination is used to select multiple objects or to extend a selection. shading language A high-level language, accessible in C, used to produce advanced imaging effects. The Apple implementation of OpenGL supports ARB_shading_language_100 . Shift JIS Shift Japanese Industrial Standard. A character encoding based on two JIS standards: JIS X 0201 and JIS X 0208. Shift JIS consists of codes from the JIS X 0208 standard that are shifted to make room for older Hankakukana codes from the JIS X 0201 standard. shadow An image painted underneath, and offset from, a graphics object such that the shadow mimics the effect of a light source cast on the graphics object. shadow object In Mach VM, a memory object that holds modified pages that originally belonged to another memory object. It is used when an object that was duplicated in a copy-on-write fashion is modified. If a page is not found in this shadow object, the original object is referenced. sidebar In the Finder, a user-specified list of disks, volumes, and other directories that allow users quick access to specific locations. signal A UNIX mechanism for manipulating a process from outside its domain. The system uses signals to deliver important messages to an application, such as whether the application executed an illegal instruction. shared secret authentication An authentication method based on a secret known to only the two parties involved. Verification of passwords is a commonly used shared secret authentication method. signal dispatch source A dispatch source used to process UNIX signals. A signal source calls your custom event handler whenever the process receives a UNIX signal. shared workgroup build In Xcode, a distributed build that works best with small to medium-sized projects that use up to ten build servers. signal-to-noise ratio See SNR. SIMD Single Instruction, Multiple Data. A computing technique used to achieve data level parallelism. Commonly employed in vector processors, this technique allows for multiple data elements to be processed in a single CPU instruction. Shark A tool for analyzing a running (or static) application. It returns metrics to help you identify potential performance bottlenecks. sheet A dialog attached to a specific window, ensuring that the user never loses track of which window the dialog belongs to. Sheets appear to slide out from underneath the window title and float above the window. A Print dialog is an example of a sheet. See also document-modal dialog. similarity searching The matching of a query string, typically consisting of a representative portion of a document, to indexed documents. A match occurs when Search Kit determines significant content 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 116 Glossary similarity between the query and an indexed document. Search Kit supports similarity searching in vector and inverted-vector indexes. Similarity searching also works in inverted indexes in Search Kit, but performance is worse. See also search. single-fork movie file A QuickTime movie file that stores both the movie data and the movie resource in the data fork of the movie file. You can use single-fork movie files to ease the exchange of QuickTime movie data between Macintosh computers and other computer systems. simple message In Mach, a message that contains neither references to ports nor pointers to data. Compare nonsimple message. single signon A feature of a security system whereby users provide authentication credentials (such as user ID and password) only once, after which they can access additional services without reauthenticating. See also authentication, ticket. simple search The matching of the terms in a query string to indexed terms using exact, character-for-character matching. Each term is matched separately. In Search Kit, by default, spaces between terms behave like Boolean AND operators. See also search. skip atom An atom of type 'skip', which you can include in a QuickTime file as a placeholder for unused space. simple statement In AppleScript, a statement that can be written on a single line. See also compound statement. slice The number of frames requested and processed during one rendering cycle of an audio unit. See also frame. simple value A value, such as an integer or a constant, that does not contain other values. slider control A control enabling users to choose among a continuous range of allowable values. Slider controls can be horizontal or vertical and can display incremental tick marks. simpleroutine In Mach, a remote procedure call that does not return a value and has no out or inout parameters. It can be used for asynchronous operations. See also routine. Small Computer System Interface See SCSI. small system font The font used for informative text in alerts, headers in lists, help tags, and text in the small versions of many controls. It is 11-point Lucida Grande Regular. Simulator See iOS Simulator application. single caret In unidirectional text, the standard text-insertion caret. In mixed-directional text, one caret that appears at the place where the user will insert the next character, given the current keyboard script. At a boundary between two direction runs, the single caret can correspond to either the primary line direction or the secondary line direction. Because changing the keyboard script in that situation changes the caret location, the single caret is also called a moving caret or jumping caret . smart card A plastic card similar in size to a credit card that has memory and a microprocessor embedded in it. A smart card can store and process information, including passwords, certificates, and keys. A smart card normally requires a personal identification number (PIN) or biometric measurement (such as a fingerprint) before releasing information and can carry out its own authentication 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 117 Glossary evaluation. Smart cards can exchange information with a personal computer through a smart card reader. SMTP Simple Mail Transfer Protocol. A protocol used to transfer email between computers, usually over Ethernet. smart group In Xcode, a group, either built-in or custom, that collect files that match a rule or pattern. You can customize the contents using wildcard patterns or regular expressions. snapshot In Xcode, a view of the state of the files in project. Snapshots allow you to experiment freely with refactoring operations. snapshot store In Xcode, the set of snapshots taken from one or more projects with the same project root. smart swash A variation of an existing glyph (often ornamental) that is contextual. Compare swash. SMB Server Message Block. A file-sharing protocol used on Windows and UNIX systems. SMB can also be used to share printers and has calls to authenticate users. It runs over several different types of networks, including TCP/IP. For most purposes, SMB has been superseded by CIFS. See also Samba. snapshotting A part of the Enterprise Objects optimistic locking mechanism, in which snapshots of database rows in memory are compared with the data in the database. SNR Signal-to-noise ratio. The range, expressed in decibels, between a nominal signal level and the noise floor. Compare dynamic range. SMB/CIFS See CIFS, SMB. S-MIME Secure Multipurpose Internet Mail Extensions. A specification that adds digital signature authentication and encryption to electronic mail messages in MIME format. SOAP XML-based, lightweight, platform-agnostic protocol used to exchange information in a decentralized, distributed environment. The protocol defines the XML elements that must be used to compose a message and how the data in a message should be processed. SOAP was originally an acronym for Simple Object Access Protocol , but as of version 1.2 of the W3C specification, the term is no longer an acronym. SMP Symmetric multiprocessing. A feature of an operating system in which two or more processors are managed by one kernel, sharing the same memory and having equal access to I/O devices, and in which any task, including kernel tasks, can run on any processor. SOAP engine Application or framework used by web service providers and consumers to process SOAP messages. SMPTE Society of Motion Picture and Television Engineers. An organization that publishes standards related to film, television, and audio. socket (1) In BSD-derived systems, a socket refers to different entities in user and kernel operations. For a user process, a socket is a file descriptor that has been allocated using socket(2). For the kernel, a socket is the data structure that is allocated when the kernel’s implementation of the socket(2) call SMPTE timecode A standard, time-based format for tagging film, video, and audio recordings to support synchronization and editing. The SMPTE timecode represents a given time in the format hours:minutes:seconds:frames. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 118 Glossary is made. (2) In AppleTalk protocols, a socket serves the same purpose as a “port” in IP transport protocols. source text A stored sequence of character codes that represents a line of text. Characters in source text are stored in input order. Compare display text. socket filter A filter that is associated with a particular socket or class of sockets, filtering in-band and out-of-band operations on the socket. A socket filter resides between a socket and the protocol layer. sparse SDK An SDK that is not a system SDK. Sparse SDKs may be provided by third parties, or you can build them yourself. spatialization The manipulation of audio signals to create perceived localization of sounds within a sound field. Compare panning. See also sound field. socket structure A data structure containing data associated with a network socket. S/PDIF Sony/Phillips Digital Interface. A consumer version of, and the inspiration for, the AES-3 format. Part of the IEC-60958 standard. Devices such as CD players and DAT recorders use S/PDIF. Software Development Kit See VM. sonogram A three-dimensional visualization of a signal’s frequency content. Typically, a sonogram’s horizontal axis is time, its vertical axis is frequency, and the visual intensity (in terms of color or dot size) of each plotted point represents energy. Also called a spectrogram. spectrogram See sonogram. speech attribute A setting defined on a speech channel that affects the characteristics of the spoken output for a subset of voices or for all voices associated with a particular synthesizer. sound field In acoustics, the space in which a sound is produced, conveyed to a listener, and perceived. In audio reproduction, the virtual space from which a monaural sound can seem to emanate. See also spatialization. speech channel A structure through which an application communicates with a specific speech synthesizer and voice. An application may have more than one speech channel open at one time, but a speech channel may not be associated with more than one synthesizer and voice at one time. SoundField A four-channel acoustic recording technique developed by the British company SoundField, Ltd. speech pitch The middle pitch of a voice, from which the actual pitches of the speech can vary with rising and falling tunes. Pitch is a combination of the average speaking frequency and its variations around that average. source control See visual context. source file In Xcode, a file used to build a product. Source files include source code files, resource files, image files, and others. source group In Xcode, a group inside a project group in the source window that contains references to actual files somewhere on the hard disk. speech rate The approximate number of words of text that a speech synthesizer speaks in one minute. speech recognition The ability for a computer to understand spoken commands or responses. source list A list in a pane of an application window used to organize and navigate data. The width of the pane is adjustable. The Finder sidebar is an example of a source list. speech synthesis The ability for a computer to audibly communicate in the language of the user. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 119 Glossary Speech Synthesis Manager A C-based API that supports extensive control over speech synthesis. splitter bar A control for dividing a window into resizable sections. speech synthesizer A component that converts text into speech. A speech synthesizer usually contains executable code, built-in dictionaries, and pronunciation rules that help it determine how to pronounce text. Also called a speech engine . split view A view that groups together two or more subviews, such as list or column views. A split view includes one or more splitter bars to adjust the relative sizes of the subviews. spool To send files to a device or program (called a spooler or daemon) that puts them in a queue for later processing. The print spooler controls output of jobs to a printer. Other devices, such as plotters and input devices, can also have spoolers. speech volume The average amplitude at which the speech channel generates speech. spin/sleep lock Any of a family of lock types characterized by some combination of the behaviors of spinlocks and mutex (sleep) locks. spool file A temporary disk file used by an application to store data. It is generally used to save memory. spinlock Any of a family of lock types characterized by continuously polling to see if a lock is available, rather than putting the waiting thread to sleep. spring In Interface Builder, an element in the size pane of the inspector window that controls the autosizing behavior of a view or control. When a spring is present, the width or height of your view grows and shrinks proportionally to its parent view. When no spring is present, the width or height of your view remains fixed. SPL Sound pressure level. A measure of sound intensity. SPL is commonly expressed as a ratio in decibels relative to 0 dB SPL, or as an absolute level in Pascals (Pa). Although SPL is sometimes used to approximately indicate loudness, the correlation of SPL to loudness is complex due to perceptual factors. See also weighting. sprite An animated image that is managed by QuickTime. A sprite is defined once and is then animated by commands that change its position or appearance. spl macro Set priority level macro. A macro that sets the current IPL. Interrupts with lower priority than the current IPL are not be acted upon until the IPL is lowered. spl macros have no effect in many parts of OS X, so their use is discouraged as a means of synchronization in new programming except when modifying code that already uses spl macros. See also IPL. sprite track A movie track populated by movie sprites. SRC Sample rate conversion. In digital audio, the process of converting PCM data from one sample rate to another. split caret A type of caret that, at the boundary between text of opposite directions, divides into two parts, a high caret and a low caret, each measuring half the line’s height. The two separate half-carets merge into one in unidirectional text. Also called a dual caret . Compare single caret. SSE Streaming SIMD Extensions. Intel’s SIMD instruction set. SSL Secure Sockets Layer. A protocol that provides secure communication over a TCP/IP connection. It uses digital certificates for authentication and digital 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 120 Glossary signatures to ensure message integrity, and can use public key cryptography to ensure data privacy. An SSL service negotiates a secure session between two communicating endpoints. SSL is built into all major browsers and web servers. SSL has been superseded by TLS (Transport Layer Security). Events sent to the standard toolbox dispatcher are automatically routed to the appropriate event targets. statement A series of lexical elements that follows a particular AppleScript syntax. Statements can include keywords, variables, operators, constants, expressions, and so on. See also compound statement, simple statement. stack frame In Xcode, information the debugger stores about each function call that your program makes. statement block In AppleScript, one or more statements enclosed in a compound statement and having an end statement. Standard Apple Plug-ins Plug-ins for standard Apple applications, such as Interface Builder, Address Book, and Quartz Composer, and preference panes. static library A library for which all referenced symbols are bound at link time. standard event handler In Carbon applications, the event handler that processes an event if the application did not install one for it. static text field Text in a dialog that users can’t modify. Standard Roman character set The 256 characters and character codes that are supplied with the Macintosh Roman script system. The Standard Roman character set consists of the Macintosh character set plus additional defined characters with character codes between $D9 and $FF. status bar In Xcode, an area at the bottom of the project window that displays messages generated when building or running the project. stem The root of a family of morphological or inflectional variants of a word. For example, “swim” is the stem of “swimmer,” “swimming,” and “swam.” standard state A new window’s initial size and position (determined by the application). See also user state, zoom button. stemming The algorithm-based removal of morphological and inflectional word components, typically endings. Language dependent. Stemming is sometimes referred to as suffix stripping , although some stemming algorithms perform prefix stripping as well. Information retrieval systems use stemming to improve search quality and to reduce index size. Search Kit does not support stemming; if needed, client applications implement it. Some stemming algorithms handle only regular variants, such as converting “swimming” to “swim,” and do not handle irregular variants, such as converting “swam” to “swim.” Standard suite The scriptability information for a set of standard AppleScript terms that scriptable applications should support if possible. The Standard suite contains commands such as count, delete, duplicate, and make, and classes such as application, document, and window. Cocoa scripting provides a great deal of automatic support for the Standard suite. standard toolbox dispatcher In the Carbon Event Manager, the default event target for events when running under RunApplicationEventLoop . 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 121 Glossary stencil buffer In image processing, memory used specifically for stencil testing. A stencil test is typically used to identify masking regions, identify solid geometry that needs to be capped, and to overlap translucent polygons. stroke (1) A drawing operation that follows a path. (2) In Ink Services, an array of points that define the path of the stylus, starting with a stylus-down event and ending when the stylus is lifted. structure region The entire area taken up by a window onscreen. stepper control A control for incrementing or decrementing a value. The control has an upward and a downward pointing arrow. strut In Interface Builder, an element in the size pane of the inspector window that controls the autosizing behavior of a view or control. When a strut is present, the distance between the edge of a view and its parent view remains fixed. When absent, the distance grows and shrinks as the size of the views change. stopword A word not to add to a search index. When Search Kit adds terms from a document to an index, it skips over words in its stopword list. storage order The order in which character codes are stored in memory. Storage order may be different from display order. stub library A library used for linking purposes. Stub libraries contain exported symbols only; they do not contain executable code. stream (1) (n.) A continuous flow of data (especially audio or video) over a transmission channel that can be interpreted as it is received, often for playback in real time. In audio, the packet boundaries used for encoding in a particular audio format may not coincide with transmission packet boundaries. (2) (v.) To send data as a stream. See also audio file stream, parser, TCP stream. style A visual attribute, other than size, applied as a systematic variation to the plain (unstyled) characteristics of a font glyph—for example bold, italic, underline, outline, shadow, condense, and extend. style attributes A collection of values and settings that override the font-specified behavior for displaying and formatting text in a style run. strength A measure of the amount of effort required to break a security system. For example, the strength of RSA encryption is believed to be related to the difficulty of factoring the product of two large prime numbers. styled text Text that may include style and font information. Not supported in AppleScript 2.0. style object An opaque object that contains a collection of stylistic attributes. Style objects can be applied to runs within a text layout object. string In AppleScript, a synonym for the text class. string atom An atom in VR media that contains text. style run A sequence of text that is contiguous in memory and in which all the characters are in the same style. Compare text run. strip style In Xcode, specifies the level of stripping performed when dead-code stripping is enabled. There are three levels of stripping available: all symbols, nonglobal symbols, debugging symbols. stylus A hand-held instrument used to enter data into the computer. Also referred to as a pen. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 122 Glossary subframework A public framework that packages a specific Apple technology and is part of an umbrella framework. Through various mechanisms, Apple prevents or discourages developers from including or directly linking with subframeworks. See also umbrella framework. suffix stripping See stemming. SUID Saved user ID. The ID used by BSD to enable a privileged process to switch in and out of privileged mode. suite Within an application’s scriptability information, a grouping of terms associated with related operations. For example, operations involving text, graphics, or databases are generally collected into separate text, graphics, and database suites. submap A collection of mappings in the VM system that is shared among multiple Mach tasks. submenu A menu that descends from another menu. The title of the submenu is a menu item in the parent menu. See also hierarchical menu. suite definition A property list that describes scriptable objects in terms of their attributes, relationships, and supported commands subpatch In Quartz Composer, a patch that is contained in a macro. suite terminology A property list that maps AppleScript terminology—the English-like words and phrases you can use in a script—to the class and command descriptions in a suite definition. subpicture A graphic bitmap overlay used in DVD-Video to create subtitles, captions, karaoke lyrics, menu highlighting effects, and so on. substring searching Matching of a term in a query string to indexed terms, with explicit wildcard characters at the start and end of the query term. A match occurs when the characters in the query term (minus the wildcard characters) match the beginning, ending, or middle of an indexed term. For example, the query string *cat* will match cat, concatenate, tomcat, and cattle. Search Kit supports substring searching in inverted and inverted-vector indexes. See also search. summarization object In Search Kit, an opaque data type representing summarization information, including the summary text. A summarization object is of type SKSummaryRef. Summary pane A pane in the Page Setup and Print dialogs that provides a textual list of the currently selected options for that dialog. superuser See root user. supervisor mode The processor mode in which certain privileged instructions can be executed, including those related to page table management, cache management, clock setting, and so on. Also known as kernel mode . suffix searching A specialized type of substring search. A suffix search involves matching of a term in a query string to indexed terms, with an explicit wildcard character at the start of the query term. A match occurs when the characters in the query term (minus the wildcard character) match the ending of an indexed term. For example, the query string *ion will match ion, lion, and version. Search Kit supports suffix searching in inverted and inverted-vector indexes. See also search, wildcard character. surface The internal representation of a single buffer that OpenGL actually draws to and reads from. For windowed drawable objects, this surface is what the OS X window server uses to composite OpenGL content on the desktop. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 123 Glossary surrogates Values that allow additional characters to be mapped to the Unicode 16-bit character set. synchronization See keyboard and font synchronization. surround sound A loudspeaker configuration with more than two loudspeakers, intended to provide an immersive audio experience. See also 5.1 Surround Sound. synchronous In Audio Queue Services, describes one of two ways to stop an audio queue. Synchronous stopping happens immediately, without regard for previously buffered audio data. In digital communications, a transmission method that requires the clock frequency of the sender and receiver to be the same. Compare asynchronous. swash A variation of an existing glyph (often ornamental) that is noncontextual. Compare smart swash. synchronous launch A launch operation in which control does not return to the calling program until the launched application has completed its launch sequence. Compare asynchronous launch. SWF file A file that contains Flash data. See Flash. symbolic link A lightweight reference to files and folders in UFS file systems. A symbolic link allows multiple references to files and folders without requiring multiple copies of these items. Symbolic links are fragile because if what they refer to moves somewhere else in the file system, the link breaks. However, they are useful in cases where the location of the referenced file or folder will not change. See also alias. sync sample A sample that does not rely on preceding frames for content. See also key frame. synonym (1) A term that an information retrieval system considers to be equivalent to another term for both indexing and querying. For example, an IR system could define “car,” “passenger vehicle,” and “automobile” to be synonyms. See also index, information retrieval, query. (2) An AppleScript word, phrase, or language element that has the same meaning as another AppleScript word, phrase, or language element. For example, the operator does not equal is a synonym for ≠. symmetric keys A pair of identical keys used to encrypt and decrypt data. See also private key. Compare asymmetric keys. symmetric multiprocessing See SMP. sync Short for synchronization . (1) The process of ensuring that the clocks of two or more systems remain locked together, counting at the same rate. This term is commonly used in the context of locking an audio track to a video track. See also clock, clock drift, SMPTE timecode. (2) In a printing dialog extension, a procedure that maintains the correspondence between the current user interface settings and their recorded values in a job ticket. (3) In Sync Services, the process of establishing and maintaining data consistency between multiple clients. syntax The arrangement of words in an AppleScript statement. syntax-aware indenting In Xcode, a feature of the text editor that gives you a number of ways to control code layout. When you use syntax-aware indenting, the editor automatically indents your code as you type. syntax description The rules for constructing a valid AppleScript statement of a particular type. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 124 Glossary syntax formatting In Xcode, formatting that uses different fonts and colors to identify particular elements in a source code file, such as keywords and comments. system output unit An Apple-supplied audio unit that connects with whichever hardware device the user has designated to be the system output. system requirement A condition that must be met by the computer (and associated operating system) in order for an installation to proceed. system direction The horizontal placement of interface elements, including the default line direction (left-to-right or right-to-left) for text in the system script. System direction is specified by the global system direction variable. system-restricted application An application that has a portion of its features restricted to specific users because of the BSD permissions system. Systeme Electronique Couleur avec Memoire See SECAM. system script The primary script system used by the operating system, such as in dialogs and menu bars. The system script affects system defaults, such as the system font, line direction, and text-formatting rules. All other scripts are secondary to the system script. system font The font used for text in menus and in modeless dialogs, and for titles of document windows. It is 13-point Lucida Grande Regular. system framework A framework developed by Apple and installed in the file-system location for system software. system sleep A sleep state that occurs when the user chooses Sleep from the Apple menu or closes the lid of a laptop computer. See also idle sleep system keychain A keychain that belongs to the system as a whole, rather than to a particular user. System keychains are usually used by system daemons and services, but can also be accessed by applications on behalf of users. One system keychain, named System.keychain, is created by the system and added by default to every user’s keychain list. tab view A control that provides a convenient way to present information in a multipane format. table In relational databases, a two-dimensional set of values corresponding to an entity. The columns of a table represent characteristics of the entity and the rows represent instances of the entity. system modal A window state in which the user cannot do anything else until the window is dismissed. You should avoid using the system-modal state if at all possible. Compare application-modal, document-modal. tail time The time, beyond an audio unit’s latency, for a nominal-level signal to decay to silence at an audio unit’ sutput ’ after it has gone instantaneously to silence at the input. Tail time is significant for audio units performing an effect such as delay or reverberation. An audio unit declares its tail time as a setup assistant. system object An object that is part of a scriptable element of OS X. target (1) In Xcode, the instructions for building a finished product from a set of files in a project—for example, a framework, library, application, or command-line tool. Each target builds a single product. (2) In AppleScript, the recipient of a system output In OS X, the hardware destination for all system sounds. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 125 Glossary command. Potential targets include application objects, script objects (including the current script), and the current application. TCP stream Transmission Control Protocol stream. A data stream used for audio delivery over networks. TCP is part of the IP (Internet Protocol) suite. It provides reliability and in-order delivery of packets.. target dependency A relationship among Xcode targets that specifies the order in which they should be built. TDM Time division multiplexing. A method of combining multiple digital signals in a single data stream by sound field samples of each signal in time. For example, to carry a stereo signal on a single stream, the stream contains alternating samples of the left and right channels: L R L R L R. targeted gesture In Ink Services, a gesture that has a defined hot spot that an application can use to determine the area to which the gesture should apply. tearing In image processing, a visual anomaly caused when part of the current frame overwrites previous frame data in the framebuffer before the current frame is fully rendered on the screen. Target Info window A window in which you can view and modify target settings. target OS version The earliest version of OS X in which the installation package is to be installed. The package is installable on the specified version and later. For example, a package whose target is OS X v10.4 can be installed on computers running OS X v10.4 and later versions. tell statement In AppleScript, a control statement that specifies the default target for the statements it contains. template (1) A pattern or model designed to guide development in accordance with a specific predefined format or structure. (2) In Xcode, a structured set of default resources (files, folders, frameworks, and so forth) necessary for a specific type of programming project. (2) In Quartz Composer, a composition file that contains a basic set of patches for a particular purpose. (3) In a WebObjects component, a file containing HTML that specifies the overall appearance of a Web page generated from the component. target template An Xcode template that specifies the target product type, a list of default build phases, and default definitions for some build settings. A target template typically includes all build settings and build phases required to build an instance of the specified product. task (1) A quantity of work to be performed. (2) A Mach abstraction consisting of a virtual address space and a port name space. A task itself performs no computation; rather, it is the context in which threads run. See also process, thread. tempo The general speed of a piece of music, often described in beats per minute (BPM). task port A kernel port that represents a task and is used to manipulate that task. See also kernel port, thread port. temporal compression In QuickTime, image compression that is performed between frames in a sequence. This compression technique takes advantage of redundancy between adjacent frames in a sequence to reduce the amount of data that is required to accurately represent each frame in the TCP/IP Transmission Control Protocol/Internet Protocol. An industry-standard protocol used to deliver messages between computers over the network. TCP/IP support is included in OS X. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 126 Glossary sequence. Sequences that have been temporally compressed typically contain key frames at regular intervals. text direction The direction in which reading proceeds. Roman text has a left-to-right direction; Hebrew and Arabic have a (predominantly) right-to-left direction; Chinese and Japanese can have a vertical direction. tempo track A special track used to synchronize all the other tracks in a sequence. See also event track. text editor In Xcode, a view that displays a file for editing. The editor can be a pane in a window or a standalone window. tentative gesture In Ink Services, Ink that the system treats tentatively as a gesture until your application either confirms the Ink is indeed a gesture or informs the system the Ink is not a gesture. The Join gesture is the only tentative gesture. text encoding The coded character set or character encoding scheme used to represent a particular piece of text. term An atomic entry in a Search Kit index, typically corresponding to a word found in one of the index’s documents. Text Encoding Conversion (TEC) Manager A pair of shared library extensions—namely, the Text Encoding Converter and the Unicode Utilities—that facilitate text encoding conversion on Mac OS–based computers. termination mode In Ink Services, the conditions that define the end of an Ink phrase. Text Encoding Converter A shared library extension that provides the services for general and algorithmic encoding conversions or multi-encoding streams. The Text Encoding Converter sometimes uses Unicode Utilities. terminology browser A graphical tool for displaying the scripting terminology for a scriptable application. Also known as a dictionary browser . tessellation An operation that reduces a surface to a mesh of polygons or a curve to a sequence of lines. text extraction In information retrieval systems, the selective copying of terms from one or more documents into an index. See also stemming, stopword. test In AppleScript, a Boolean expression that specifies the conditions of a filter or an if statement. test provisioning profile A provisioning profile issued to users not on an iOS application developer team. It allows them to install and test applications that have not been published to the App Store. text face An algorithmic way for your application to produce typestyles. text input field A rectangular area in which the user enters text or modifies existing text. Also called an editable text field , it supports keyboard focus and password entry. texel In image processing, a texture element used to specify the color to apply to a fragment. text A set of specific symbols that, when displayed in a meaningful order, conveys information. text layout object An opaque object that contains information to control the display and formatting of the text to which the object is associated. text area The space on a display device within which the text should fit. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 127 Glossary text macro In Xcode, a menu item or keystroke that lets you insert common constructs and blocks of code. texture mapping In OpenGL, the process of applying a texture to a primitive. texture matrix A 4 x 4 matrix that OpenGL uses to transform texture coordinates to the coordinates that are used for interpolation and texture lookup. text manipulation System-level procedures used to order and compare characters, determine line breaks, determine text directionality, and keep track of character properties, such as case. texture object In OpenGL, an opaque data structure used to store all data related to a texture. A texture object can include such things as an image, a mipmap, and texture parameters (width, height, internal format, resolution, wrapping modes, and so forth). text object An opaque structure that the Multilingual Text Engine uses to handle text formatting at a document level. text run A sequence of text that is contiguous in memory and in which all characters are in the same font. Compare run. text width The area between the margins; it is the length available for displaying a line of text. text segment For text layout, the portion of a style run that falls on a single text line. (It may be the entire style run.) Most text measuring and drawing routines work on a single text segment at a time. TGT Ticket-granting ticket. In Kerberos, a credential presented to the ticket-granting server in order to obtain a ticket. The ticket can then be used to gain access to a secure server. The use of TGTs and tickets enable the single signon feature, whereby the user need authenticate only once, after which they can access additional services without reauthenticating (by reentering their password, for example). See also authentication, identification. Text Services Manager (TSM) The Mac OS technology that provides text services such as input methods. TSM handles communication between client applications that request text services and the software modules, known as text service components, that provide them. thread A flow of execution in a process. Each thread has its own stack space but otherwise shares memory with other threads in the same process. A thread consists of a program counter, a set of registers, and a stack pointer. See also task. text style A visual attribute, other than size, applied as a systematic variation to the plain (unstyled) characteristics of a font’s glyphs. Some typical text styles include plain, bold, italic, underline, outline, shadow, condensed, and extended. thread port A kernel port that represents a thread and is used to manipulate that thread. See also kernel port, task port. text to speech (TTS) The ability of the computer to convert text into spoken words. thread-safe code Code that can be executed safely by multiple threads simultaneously. texture In OpenGL, image data used to modify the color of rasterized fragments; can be one-, two-, three- dimensional or a cube map. See also OpenGL texture. threshold A preset signal level at which some sort of processing is activated. For example, a compressor audio unit can allow you to specify the threshold above which compression begins. texture cache A pool of OpenGL textures. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 128 Glossary thumbnail picture In QuickTime, a picture that can be created from an existing image that is stored as a pixel map, a picture, or a picture file. A thumbnail picture is useful for creating small representative images of a source image and in previews for files that contain image data. time-based authentication A form of shared secret authentication in which the secret is changed periodically in a way known only to the two parties involved. time-based data Data that changes or interacts with the user along a time dimension. QuickTime is designed to handle time-based data. tick 1/60 second. ticket (1) In printing, an opaque data structure used by the system, printer modules, and printing dialog extensions to communicate information about a print job. Tickets are usually named for the type of information they contain, such as page format ticket and paper info ticket. (2) In security, a credential that a user can use to prove their identity. See also authentication, identification, Kerberos ticket. timecode A standardized indexing system for identifying specific portions of a audio file. Timecodes are often used for synchronizing or editing audio data. See also SMPTE timecode. timecode media A media structure of type 'tmcd' that is used to store timecode data. timecode track A movie track that stores external timing information, such as SMPTE timecodes. ticket-granting server In Kerberos, the server that issues a ticket when presented with a TGT (ticket-granting ticket). See also KDC. time coordinate system A set of values that defines the context for a time base. A time coordinate system consists of a time scale and a duration. Together, these values define the coordinate system in which a time value or a time base has meaning. ticket-granting ticket See TGT. tiling In Quartz, the process of rendering pattern cells to a portion of a page. Quartz has three tiling options—no distortion, constant spacing with minimal distortion, and constant spacing. timeline A visual representation of an audio signal over time. timer A kernel resource that triggers an event at a specified interval. The event can occur only once or can be recurring. Timers are one of the input sources for run loops. Timers are also implemented at higher levels of the system, such as NSTimer in Cocoa. timbre The perceived quality of a sound as distinct from pitch, volume, envelope, and duration. For example, a tuning fork can be described as having a “gentle” timbre, while a strongly hit crash cymbal can be described as having a “harsh” timbre. timer source A source of synchronous events for a thread. Timers generate one-shot or repeated events at a scheduled future time. time base A set of values that define the time basis for an entity, such as a QuickTime movie. A time base consists of a time coordinate system (that is, a time scale and a duration) along with a rate value. The rate value specifies the speed with which time passes for the time base. time scale The number of time units that pass per second in a time coordinate system. A time coordinate system that measures time in sixtieths of a second, for example, has a time scale of 60. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 129 Glossary time-sharing policy In Mach, a scheduling policy in which a thread’s priority is raised and lowered to balance its resource consumption against other timesharing threads. communicating endpoints. TLS is built into recent versions of all major browsers and web servers. TLS is the successor to SSL. Although the TLS and SSL protocols are not interoperable, Secure Transport can back down to SSL 3.0 if a TLS session cannot be negotiated. time unit The basic unit of measure for time in a time coordinate system. The value of the time unit for a time coordinate system is represented by the formula (1/time scale) seconds. A time coordinate system that has a time scale of 60 measures time in terms of sixtieths of a second. toggled menu item A menu item or a set of two menu items that change between two states (for example, Turn Grid On and Turn Grid Off ). token (1) In code completion, a string that does not contain spaces. (2) For documentation sets, the element used to associate a symbol with its reference documentation. The element includes a unique identifier representing the symbol, the location of the reference documentation for that symbol, summary information about that symbol, and information about related documentation and symbols. time value A value that specifies a number of time units in a time coordinate system. A time value may contain information about a point in time or about a duration. title The largest unit of a DVD-Video disc (other than the entire volume or side). Usually a movie, TV program, music album, or the like. A disc can hold up to 99 titles, which can be selected from the disc menu. token field A control that creates a token out of a user’s text input. title bar The bar at the top of the window that displays its name. The title bar can also contain controls and a proxy icon. token identifier In Xcode, the unique identifier for a symbol described in a tokens file. title search In Xcode, a search type that finds the documents whose titles start with, contain, or match the search term. tokens file In Xcode, a file that associates symbol names with locations in documentation. A tokens file is used to create the symbol index for a documentation set, which support fasts API lookup. TLD Tag library descriptor. An XML document that describes a tag library. A JSP (JavaServer Pages) container uses the information contained in the TLD file to validate a JSP page’s tags. to-many relationship (1) In relational databases, a relationship in which each source record has zero to many corresponding destination records. For example, a department has many employees. (2) In key-value coding, a property whose value is a collection of related objects. In an AppleScript scripting definition file, it is represented by an element element. TLS Transport Layer Security. A protocol that provides secure communication over a TCP/IP connection such as the Internet. It uses digital certificates for authentication and digital signatures to ensure message integrity, and can use public key cryptography to ensure data privacy. A TLS service negotiates a secure session between two tool palette A collection of buttons and other controls in a panel. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 130 Glossary toolbar A collection of buttons at the top of a window just below the title bar. A toolbar can be hidden or revealed with a toolbar button in the title bar. TosLink An optical cable standard used to transmit digital audio signals. Short for ToshibaLink . track A Movie Toolbox data structure that represents a single data stream in a QuickTime movie. A movie may contain one or more tracks. Each track is independent of other tracks in the movie and represents its own data stream. Each track has a corresponding media structure, which describes the data for the track. See also channel, event track. toolbar button A clear oblong button at the right end of a window’s title bar that shows and hides the toolbar (if one exists). toolbox dispatcher See standard toolbox dispatcher. toolbox object class A collection of event handlers and data that defines a custom object such as a control or window. track boundary region In QuickTime, a region that describes the area occupied by a track in the track’s coordinate system. QuickTime obtains this region by applying the track clipping region and the track matte to the visual image contained in the track rectangle. to-one relationship (1) In relational databases, a relationship in which each source record has exactly one corresponding destination record. For example, each employee has one job title. (2) In key-value coding, a property whose value has properties of its own. In an AppleScript scripting definition file, it is represented by a property element. track clipping region In QuickTime, the clipping region of a track in the track’s coordinate system. QuickTime applies the track’ slipping ’ region and the track matte to the image contained in the track rectangle to obtain the track boundary region. Only that portion of the track that lies in the track boundary region is then transformed into an image in the movie coordinate system. topic One of the message distribution center types for J2EE-based applications. Message senders send messages only to topics instead of specific applications, while only the applications interested in receiving messages sent to a particular topic subscribe to the topic and, therefore, receive the messages sent to it. A topic can have one or more subscribers. Any message sent to the topic is broadcasted to all the topic’s subscribers. track header atom A QT atom that specifies the characteristics of a track in a QuickTime movie. track height The height, in pixels, of the track rectangle in a QuickTime movie. top-level specifier In a nested object specifier, an object that has no container specifier. It represents the outermost container in the containment hierarchy. In most cases, the application object is the top-level specifier. tracking Kerning between all glyphs in a line of text, not just the kerning pairs already defined by the font. You can increase or decrease interglyph spacing by adjusting the tracking setting. See also tracking setting. Compare kerning. top-side bearing The white space between the top of the glyph and the visible beginning of the glyph. tracking setting A value that specifies the relative tightness or looseness of interglyph spacing. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 131 Glossary track input map A structure of QT atoms that specifies how secondary data for a track is to be interpreted (clipping, blending, and so forth). track rectangle A rectangle that completely encloses the visual representation of a track in a QuickTime movie. The width of this rectangle in pixels is referred to as the track width; the height, as the track height. track load settings In QuickTime, information that specifies how and when a track is to be preloaded before running in a movie. track reference In QuickTime, a data structure that defines the relation between movie tracks, such as the relation between a timecode track and other tracks. See also timecode track. track matte In QuickTime, a pixel map that defines the blending of track visual data. The value of each pixel in the pixel map governs the relative intensity of the track data for the corresponding pixel in the result image. QuickTime applies the track matte, along with the track clipping region, to the image contained in the track rectangle to obtain the track boundary region. See track boundary region, track matte, track rectangle. track width The width, in pixels, of the track rectangle in a QuickTime movie. trailing edge The edge of a glyph that is encountered last when reading text of that glyph’s language. For glyphs of left-to-right text, the trailing edge is the right edge; for glyphs of right-to-left text, the trailing edge is the left edge. track movie boundary region In QuickTime, a region that describes the area occupied by a track in the movie coordinate system, before the movie has been clipped by the movie clipping region. The movie boundary region is built up from the track movie boundary regions for each of the movie’s tracks. trailing frames In audio data format conversion, frames of audio data that follow, in time, the nominal ending frame for an input stream. See also priming. Compare leading frames. transaction A set of actions that is treated as a single operation that either succeeds completely (commit) or fails completely (rollback). track offset In QuickTime, the blank space that represents the intervening time between the beginning of a movie and the beginning of a track’s data. In an audio track, the blank space translates to silence; in a video track, the blank space generates no visual image. All of the tracks in a movie use the movie’s time coordinate system. That is, the movie’s time scale defines the basic time unit for each of the movie’s tracks. Each track begins at the beginning of the movie, but the track’s data might not begin until some time value other than 0. transformation (1) An alteration to a coordinate system that defines a new coordinate system. Standard transformations include rotation, scaling, and translation. A transformation is represented by a matrix. (2) A refactoring operation that modifies source code. transformation matrix A 3-by-3 matrix that defines how to map points from one coordinate space into another coordinate space. transition animation An animation that uses a Core Image filter to apply a visual effect to an animation object being displayed or hidden. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 132 Glossary translation An operation that moves the origin of the coordinate space by the number of units specified for the x and y axes. try statement In AppleScript, a two-part compound statement that contains a series of AppleScript statements, followed by an error handler to be invoked if any of those statements cause an error. transmission channel A hardware or software conduit for the conveyance of a data stream or an analog signal. tween data In QuickTime, the data in a tween track, such as interpolation values. transparency layer A composite of two or more objects that Quartz treats as a single object when applying effects, such as shadows. tweening A process of interpolating new data between given values in conformance to an algorithm. It is an efficient way to expand or smooth a QuickTime movie’s presentation between its actual frames. transparent authentication Authentication without intervention by the user. After unlocking the keychain, the user does not have to log in separately to any services whose passwords are stored in the keychain. tween track In QuickTime, a modifier track that performs a specific kind of tweening, such as path-to-matrix rotation. Transport Layer Security See TLS. twos-complement encoding A system for digitally encoding sound that stores the amplitude values as a signed number—silence is represented by a sample with a value of 0. For example, with 8-bit sound samples, twos-complement values would range from –128 to 127, with 0 meaning silence. The Audio Interchange File Format (AIFF) stores samples in twos-complement form. Compare offset-binary encoding. trim frames Frames added to the beginning or end of a nub to pad the audio data. Trim frames added before the audio data are typically used to prime an audio decompressor. See also webpage template, priming, priming frame. triple Three values that consist of an attribute tag, a value for that tag, and the size of the value. In ATSUI, triples are used to specify style, line, and layout attributes. type-ahead The queuing of keystrokes for processing later. It occurs when the user types faster than the computer can handle or when the computer is unable to process the keystrokes. trust See level of trust. trust policy A set of rules that specifies the appropriate uses for a certificate that has a specific level of trust. For example, the trust policy for a browser might state that if a certificate has an SSL certificate extension, but the certificate has expired, the user should be prompted for permission before a secure session is opened with a web server. type-definition dictionary A dictionary, specified in an application’s bundle information property list, that declares a particular document type that the application claims to handle. Compare scheme-definition dictionary. typestyle See text style. trusted application An application that can read a keychain item’s secret when the keychain is unlocked. See also Unicode Utilities. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 133 Glossary typographic bounding rectangle The smallest rectangle that encloses the full span of the glyphs from the ascent line to the descent line. See also image bounding rectangle. Unicode Unicode is an ISO standard for universal worldwide character encoding developed by a consortium that includes Apple. Unicode has enough capacity to handle unique encodings for all characters available in all scripts, including the 2-byte script systems such as Chinese, Japanese, and Korean. typographic point A unit of measurement describing the size of glyphs in a font. There are 72.27 typographic points per inch, in contrast to 72 points per inch in the Mac OS. Unicode code point A unique number that represents a character and allows it to be represented in an abstract way, independent of how it is rendered. UDDI Universal Description, Discovery and Integration. A searchable directory of web services that web service requesters can use to search for web services and obtain their WSDL documents. Unicode decomposition The splitting of a composite glyph into its component parts, such as a base character and a combining mark. UDF Universal Disk Format. The file-system format used in DVD disks. Unicode Utilities A shared library extension that provides table-based conversion between Unicode and other encodings. UDP User Datagram Protocol. A lightweight and efficient connectionless datagram transport protocol. Used to send self-routing data throughout a network. unidirectional text A sequence of text that has a single line direction. Compare bidirectional text. UFS UNIX file system. An industry-standard file-system format used in UNIX-like operating systems such as BSD. UFS in OS X is a derivative of 4.4BSD UFS. Its disk layout is not compatible with other BSD UFS implementations. uniform resource locator See URL. uninitialize To return an audio unit to its unconfigured state. Compare reset. UID User ID. In BSD, the UID is a unique attribute of a user account that is used to identify the user. Each file system object and each process has an associated UID. See also file UID, GID, UUID. uniquing In relational databases, a mechanism to ensure that, within a given context, only one object is associated with each row in the database. unit test A piece of code that exercises some part of an application. A unit test provides a specific input and expects the application to return a specific output. umbrella framework A system framework that includes and links with constituent subframeworks and other public frameworks. An umbrella framework “contains” the system software defining an application environment or a layer of system software. See also subframework. unity gain A gain of 0 dB. universal binary An executable file that can contain code and data for more than one architecture. You can create a single binary file that runs on both PowerPC-based and Intel-based Macintosh unary operator An operator that derives a new value from a single value. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 134 Glossary computers. In Xcode, the Architectures (ARCHS ) build setting lets you specify which architectures Xcode builds for. UPL Universal page list. A data structure used when communicating with the virtual memory system. UPLs can be used to change the behavior of pages with respect to caching, permissions, mapping, and so on. universal binaries Executable files containing object code for more than one machine architecture. UPP Universal procedure pointer. A generalized procedure pointer that allows code with different calling conventions to call each other. Some Carbon functions require you to pass UPPs for callbacks because the calling routine doesn’t know in advance if your code is Mach-O based or CFM-based. universal procedure pointer See UPP. Universal Serial Bus See USB. unlocked In Keychain Services, a state in which a keychain has a key in memory that can be used to encrypt or decrypt items in that particular keychain. A keychain is considered unlocked after its password has been entered (by the user or programmatically). An unlocked keychain can provide access to its secrets, subject to ACL checks, until it is locked again. URI Uniform Resource Identifier. The web naming and addressing technology. A URI is a string of characters that identify a resource. Some typical URI schemes are HTTP and FTP. URL Uniform resource locator. A string, in a standard format, designating a file, web page, or other resource, typically (but not necessarily) to be accessed via the Internet. A URL is one type of URI. See also virtual address. unordered tasks In Xcode, tasks with no inputs and outputs, or tasks whose inputs are not the outputs of other tasks and whose outputs are not the inputs of other tasks. Compare ordered tasks. unranked searching See inclusion/exclusion searching. URL Loading System An API that you can use to access the contents of http://, https://, and ftp:// URLs. Because https:// websites use SSL (Secure Sockets Layer) or TLS (Transport Layer Security) to protect data transfers, you can use the URL Loading System as a secure transport API. The URL Loading System is layered on top of CFNetwork. untargeted gesture In Ink Services, a gesture that does not have a defined hot spot. An application should apply the gesture to the current selection or insertion point. update conflict In database application development, the problem of multiple users or processes accessing and updating the same set of data simultaneously. URL type A family of URLs characterized by a given scheme component. Compare document type. USB Universal Serial Bus. A multiplatform bus standard for connecting hardware devices, such as computers, keyboards, and audio devices. Specified by the USB Implementers Forum (USB-IF), an international industry standards body. update region A region maintained by the Window Manager that includes the parts of a window’s content region that need updating. update strategy In database application development, a strategy for managing update conflicts. See also update conflict. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 135 Glossary user client An interface provided by an I/O Kit family, that enables a user process (which can’t call a kernel-resident driver or other service directly) to access hardware. In the kernel, this interface appears as a driver object called a user client ; in user space, it is called a device interface and is implemented as a CFPlugin object. See also device interface. in user space. Compare kernel space. (2) In Quartz 2D, the device-independent coordinate system used for drawing. user state A window’s user-defined size and position. See also standard state, zoom button. using terms from statement A control statement that instructs AppleScript to use the terminology from the specified application in compiling the enclosed statements. user data Auxiliary data that your application can store in a QuickTime movie, track, or media structure. The user data is stored in a user data list; items in the list are referred to as user data items . Examples of user data include a copyright, date of creation, name of a movie’s director, and special hardware and software requirements. See also user data item, user data list. UTF-8 8-bit Unicode Transformation Format 8. A format used to represent a sequence of 16-bit Unicode characters with an equivalent sequence of 8-bit characters, none of which are zero. This sequence of characters can be represented using an ordinary C-language string. user data item In QuickTime, a single element in a user data list, such as a modification date or copyright notice. UTF-16 16-bit Unicode Transformation Format. A form of Unicode in which 16-bits are used to encode a character. user data list The collection of user data for a QuickTime movie, track, or media. Each element in the user data list is called a user data item . UUID Universally Unique Identifier. A type of UID or GID that is unique across all systems and all networks. user-defined command In AppleScript, a command that is implemented by a handler defined in a script object. V1 In Core Audio, the original version of the audio unit interface, deprecated in OS X v10.2 and unsupported starting in OS X v10.5. V1 audio units differ from V2 audio units in that they supported fan out, supported interleaved streams, and used a component type and subtype approach different from that of V2. New development should be done with the V2 audio unit interface. Compare V2. user focus The window or text field control to which keyboard input is directed. The user can change the user focus by using the mouse or (sometimes) the Tab key. user ID Data, usually a character string, used to identify a user for a service or application. V2 In Core Audio, the current version of the audio unit interface, recommended since OS X v10.2 and the only supported version starting with OS X v10.5. Compare V1. user size The window size determined by the user. user space (1) Virtual memory outside the protected partition in which the kernel resides. Applications, plug-ins, and other types of modules typically run 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 136 Glossary valid extension A filename extension that does not contain spaces, periods, or characters that are not supported by the underlying file system. Compare active extension. advantage of vector graphics over bitmap graphics (or raster graphics) is that any element of the picture can be changed at any time because each element is stored as an independent object. Another advantage of vector graphics is that the resulting image file is typically smaller than a bitmap file containing the same image. Examples of vector-image file types are PDF, encapsulated PostScript (EPS), and SVG. Compare raster graphics. validation A mechanism to ensure that user-entered data lies within specified limits. variable A named container in which to store a value. vector index In Search Kit, an index containing document URL objects, as keys, mapped to the terms that each document contains. See also index, inverted index, inverted-vector index variable bit rate See VBR. variation axis A range of values used to produce different type styles for a font. For example, a font that has a weighting axis could be displayed with weights that range from 0.7 point (light) to 1.3 points (bold). It is possible to combine variations. For example, font width variations can be combined with weighting variations to produce font variations ranging from light, narrow to bold, wide. vector processor A processor that can perform arithmetic on several pairs of numbers simultaneously. Also called an array processor . verb-first command In AppleScript, a script command that invokes its performDefaultImplementation method. With a verb-first command, a single method performs the action (or verb) on any number of objects. Compare object-first command. VBR Variable bit rate. An encoding method available for some compression formats, such as AAC, that allows bit rate to vary according to the source material. The aim is to provide consistent perceived audio quality while minimizing file size. It does this by increasing the bit rate for difficult-to-encode portions and decreasing the bit rate for easy-to-encode portions. Compare average bit rate, constant bit rate. version number See revision number. versioned bundle A type of bundle that allows for multiple versions of framework code and header files to be stored inside the bundle. vector A grouped series of numbers. Commonly represented either as a row of numbers [1, 2, 3, 4] or a column of numbers. It is analogous to an array. versioning With frameworks, schemes to implement backward and forward compatibility of frameworks. Versioning information is written into a framework’s dynamic shared library and is also reflected in the internal structure of a framework. See also major version, minor version. vector code Code that makes use of available on-board vector processors. vImage uses vector code. vertex A three-dimensional point. A set of vertices specify the geometry of a shape. Vertices can have a number of additional attributes such as colors and texture coordinates. vector graphics The creation of digital images through a sequence of commands or mathematical statements that place lines and shapes in a two-dimensional or three-dimensional space. One 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 137 Glossary vertex array A data structure that stores a block of data that specifies such things as vertex coordinates, texture coordinates, surface normals, RGBA colors, color indices, and edge flags. these addresses onto physical memory only when necessary, using disk memory at other times. Compare physical address. virtual destination In Core Audio, a designation by a software MIDI device indicating that it can receive MIDI data. Compare virtual source. vertical reflect A type of geometric operation that reflects an image about its x-axis. vertical shear An image filter that shifts pixels along the y-axis to create an effect that’s similar to physical shearing. virtual machine See VM. virtual memory See VM. virtual screen A combination of hardware, renderer, and pixel format that OpenGL selects as suitable for an imaging task. When the current virtual screen changes, the current renderer typically changes. VFS Virtual File System. A set of standard internal file-system interfaces and utilities that facilitate support for additional file systems. VFS provides an infrastructure for file systems built into the kernel. virtual source A designation by a software MIDI device indicating that it can transmit MIDI data. Compare virtual destination. VIDEO_TS The filename used for the video directory or folder on a standard-definition DVD disc volume. Files inside this directory contain pointers to the sectors on the disc that hold the program streams. visible region The portion of a window’s content region that is visible to the user. view font The default font used in text and lists. This may be user adjustable, as it is in the Finder. visual context An abstract space that indicates where drawing should occur. For example, an OpenGL context specifies where OpenGL drawing should occur. A visual context is typically associated with an NSView or HIView object. View menu A menu that provides commands that affect what users see in a window. In the Finder, for example, the View menu contains commands for displaying windows as columns, icons, or lists. VM (1) Virtual machine. A simulated computer in that it runs on a host computer but behaves as if it were a separate computer. The Java virtual machine works as a self-contained operating environment to run Java applications and applets. (2) Virtual memory. The use of a disk partition or a file on disk to provide the facilities usually provided by RAM. The virtual-memory manager in OS X provides either a 32-bit or 64-bit protected address space for each task (depending on the options used to build the task) and facilitates efficient sharing of that address space. view rectangle In MLTE, the rectangle defining the portion of the window within which text is actually displayed. Text drawn in the destination rectangle is made visible to the application user in the view rectangle. views In Cocoa, objects that support drawing. virtual address A memory address that is usable by software. Each task has its own range of virtual addresses, which begins at address zero. The Mach operating system makes the CPU hardware map 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 138 Glossary vnode An in-memory data structure containing information about a file. WAR Web application archive. A file created using the jar utility (and saved with the .war extension) that contains all the files that make up a web application. vnode pager In Mach, one of the built-in pagers. The vnode pager maps files into memory objects. See also default pager, pager. watchpoint In Xcode, a place in code that pauses execution of the program whenever the value of the watched item changes. voice A component containing data and, optionally, executable code that helps to shape the sound of synthesized speech. WAV A chunk-based digital audio file format originally developed for IBM-compatible PCs. Although WAV files can hold compressed audio data, they most commonly hold uncompressed linear PCM data. WAV is a variant of the RIFF bitstream format. See also RIFF. VoiceOver A spoken user interface technology for visually impaired users. VoiceOver is part of OS X. volume (1) A storage device or a portion of a storage device that is formatted to contain folders and files of a particular file system. A hard disk, for example, may be divided into several volumes (also known as partitions ) (2) In psychoacoustics, the average perceived loudness of a sound. Compare level. waveform The shape of a signal when visualized as a graph showing its variation in amplitude over time. wavelength The span of one complete cycle in a repeating waveform. volume format The structure of file and folder (directory) information on a hard disk, a partition of a hard disk, a CD-ROM, or some other volume mounted on a computer system. Volume formats can specify such things as multiple forks (HFS and HFS+), symbolic and hard links (UFS), case sensitivity of filenames, and maximum length of filenames. See also file system. web application A file structure that contains servlets, JSP pages, HTML documents and other resources. This structure can be deployed on any servlet-enabled web server. Web Assistant Tool used to customize a Direct to Web application. web component An object (of the WOComponent class) that represents a webpage or a reusable portion of one. volume requirement A test that compares the value of a volume property (such as free space) with a value. Volume requirements determine whether the user can choose a particular volume as the destination volume of a product package. WebDAV Web-based Distributed Authoring and Versioning. An extension of HTTP that allows collaborative file management on the web. VR See QuickTime VR. WebObjects Builder An application used to edit web components. V-Twin See AIAT. WaitNextEvent The function that drove the event loop in older versions of the Mac OS. See also Classic Event Manager. WebObjects Deployment A software package that allows you to deploy WebObjects applications on an intranet or the web. It includes tools to design 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 139 Glossary applications using an object-oriented approach. You need to install a WebObjects deployment license on computers on which you want to install this package. wildcard character An operator used in a query that indicates matching on any character. In Search Kit, the wildcard character is the asterisk. Depending on usage, the wildcard character can indicate prefix, suffix, or substring searching. See also Roman keyboard script, query. webpage template An HTML file that specifies the overall appearance of a webpage generated from a web component. window The primary means of displaying screen information on Mac computers. web server An application that serves webpages to web browsers using the HTTP protocol. In WebObjects, the web server lies between the browser and a WebObjects application. When the web server receives a request from a browser, it passes the request to the WebObjects adaptor, which generates a response and returns it to the web server. The web server then sends the response to the browser. Also called an HTTP server . window layering The layering of windows according to the window class hierarchy. Compare window ordering. Window menu A menu that contains commands for managing document windows. The menu lists an application’s open document windows, including minimized windows, in the order in which they were opened. web service A network-based repository of processes or tasks that can be used by applications to access data or execute operations across disparate platforms. window ordering The layering of windows within a specific window class. Compare window layering. window reference A pointer to an opaque data structure that defines a window. All access to a window or its attributes is through the window reference. Web Services Assistant Application used to customize a Direct to Web Services applications. weighting Systematic adjustment of a measurement to highlight a particular criterion. For example, SPL (sound pressure level) measurements can be weighted to approximate how people perceive sound, placing more emphasis on midrange frequencies than on higher or lower ones. window server A systemwide process that is responsible for rudimentary screen displays, window compositing and management, event routing, and cursor management. It coordinates low-level windowing behavior and enforces a fundamental uniformity in what appears on the screen. wheel group In BSD, a special group, membership in which confers on users the ability to become the root user by using the su utility on the command line. Users who are not in the wheel group can’t become the root user, even if they have the correct password. In OS X, the admin group is used for this purpose rather than the wheel group. wired memory A range of memory that the virtual-memory system does not page out or move. The memory involved in an I/O transfer must be wired down to prevent the physical relocation of data being accessed by hardware. In the I/O Kit memory is wired when the memory descriptor widget An HTML-based program that runs in the Dashboard layer of the system. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 140 Glossary describing the memory prepares the memory for I/O (which happens when its prepare method is invoked). WorldScript A group of Mac OS managers, extensions, and resources that facilitate multilingual text processing. wired sprite A sprite such as a clickable button that has wired actions associated with it. WOServices A WebObjects service that monitors wotaskd processes. Its main duty is to monitor wotaskd and restart it if it dies or when the host is restarted. The implementation of this service is platform dependent. with-stream shift A uniform shift parallel to the baseline of the positions of individual pairs or sets of glyphs in the style run. Compare cross-stream shift. wotaskd WebObjects task daemon. A WebObjects Deployment tool that manages the instances on an application host. It’s used by Monitor to propagate site configuration changes throughout the site’s application hosts. with timeout statement An AppleScript control statement that specifies the amount of time AppleScript waits for application commands to complete before stopping execution of the script. writing system A set of characters and the basic rules for their use in creating a visual depiction of language. Writing systems may differ in the direction in which their characters and lines run, the size of the character set used, and the context sensitivity of character selection. Writing systems include Roman, Japanese, Arabic, and Hebrew. Compare script system. with transaction statement An AppleScript control statement that allows you to take advantage of applications that support the notion of a transaction—a sequence of related events that should be performed as if they were a single operation, such that either all of the changes are applied or none are. WOA WebObjects application bundle. A bundle that stores all the files needed by a WebObjects application. WSDL Web Services Description Language. XML-based language used to describe web services. Web service consumers can dynamically parse a WSDL document to determine the operations a web service provides and how to execute them. word wrap The automatic continuation of text from the end of one line to the beginning of the next without breaking in the middle of a word. WSS-Core Web Services Security Core Specification. A specification that defines a set of SOAP extensions that can be used to provide message-level data integrity and confidentiality. work loop A gating mechanism that ensures single-threaded access to the data structures and hardware registers used by a driver. Specifically, it is a mutex lock associated with a thread. A work loop typically has several event sources attached to it; they use the work loop to ensure a protected, gated context for processing events. See also event source. X.509 A standard for digital certificates promulgated by the International Telecommunication Union (ITU). The X.509 ITU standard is widely used on the Internet and throughout the information technology industry for designing secure applications based on a PKI (public key infrastructure). workspace The area in the Quartz Composer development tool used to assemble patches. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 141 Glossary Xcode An integrated development environment used to develop iOS and Mac applications. Xcode incorporates editor, compiler, debugger, linker, and other tools and resources. XNU X is Not UNIX. The OS X kernel. XNU combines the functionality of Mach and BSD with the I/O Kit, the driver model for OS X. XSLT Extensible Stylesheet Language Transformations. A specification that allows the conversion of an XML document into another XML document or any other type of document. Xcode application The main application of the Xcode integrated development environment (IDE). It manages the other applications that are part of Xcode and provides the main user interface used to develop software products. XSLT stylesheet A file written in XSLT that specifies how a source document is to be converted into another document. Xcode project A group that contains the source files, libraries, media, and other resources needed to build a product. XSLT transformer Software that converts an XML document into another document using an XSLT stylesheet. xib file An XML-based version of a nib file. Xib files are the preferred format to use during development of your application. At build-time, they are compiled into nib files so that they can be deployed in your application bundle. zoom button A control that toggles a window between its standard state and its user state. XML Extensible Markup Language. A metalanguage containing rules for constructing specialized markup languages. XML is very flexible, allowing users to define their own tags. XML is a dialect of SGML (Standard Generalized Markup Language). XML namespaces A specification that allows qualifying element names by associating element-name prefixes to URIs. XML parser A software engine that reads and writes XML documents. XML-RPC A simple protocol for making remote procedure requests to Internet-based servers. XML Schema A specification used to describe the structure of XML documents. XML Schema is more powerful than document type definition (DTD) because it includes facilities to specify the data type of elements and it is based on XML. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 142 Document Revision History This table describes the changes to OS X Glossary . Date Notes 2010-07-09 Changed occurrences of "iOS" to "iOS". 2009-11-17 New document that explains OS X terms as of OS X v10.6. 2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved. 143 Apple Inc. Copyright © 2010 Apple Inc. All rights reserved. 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