OS X Glossary - Defined Term

OS X Glossary - Defined Term
OS X Glossary
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.
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.
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
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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.
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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.
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advance delta The distance between the end of
one glyph’s advance and the next glyph’s real
'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
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
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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
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
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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
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
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
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.
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
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
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.
AppleTalk A suite of network protocols that is
standard on Macintosh computers and can be
integrated with other network systems, such as the
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
application bundle A bundle containing the
executable code of an application and its associated
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
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
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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
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.
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,
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
attach In OpenGL, an operation that establishes a
connection between two existing objects. Compare
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.
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
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
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,
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
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.
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
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)
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.
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
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
binding rules The rules used by Launch Services to
determine an item’s default application according
to the binding information in the Launch Services
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.
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
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
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.
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
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
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
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.
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
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.
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
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
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
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
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.
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
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
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.
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
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
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.
a consonant, a vowel, a dot to soften the
pronunciation of the consonant, and a cantillation
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
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.
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
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.
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
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
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
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.
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
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
2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved.
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
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
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.
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
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
configuration unit In Xcode, a group of
configuration files joined together by #include
2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved.
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
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
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
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.
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
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
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
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.
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
2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved.
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
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
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
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
cubic curve A curve defined by a cubic equation.
See also B�zier 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.
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
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
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.
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
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
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.
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
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.
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
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
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.
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
device advance The number of pixels of the
advance for the glyph as actually drawn on the
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-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
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.
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.
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
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.
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
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
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.
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
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
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
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.
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
driver See device driver.
driver layer I/O Kit drivers for various networking
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
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
2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved.
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
DVD An optical storage medium that provides
greater capacity and bandwidth than CD-ROM; DVDs
are frequently used for multimedia as well as data
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
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,
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
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
[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.
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
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
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.
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
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
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
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.
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
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
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.
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
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
IOTimerEventSource, and IOCommandGate.
executable An application that uses a project’s
product and can be launched in order to debug that
executable environment Defines how Xcode
should execute a product in response to the Go
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
2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved.
exit statement In AppleScript, a statement used in
the body of a repeat statement to exit that
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
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.
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
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
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.
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
file type atom An atom of type 'ftyp', which
defines which file specifications a file is compatible
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
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.
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
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
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
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.
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
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
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
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.
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.
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
Function menu In Xcode, a pop-up menu in the
navigation bar that lists the identifiers in the current
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.
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
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
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
glyph orientation A value that specifies which
direction (vertical or horizontal) glyphs should be
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
glyph outline The curves that make up the shape
of the glyph.
2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved.
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
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
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.
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.
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,
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.
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
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.
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
ID reference form In AppleScript, a reference form
that specifies an object by the value of its ID
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
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
2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved.
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
imaging system The system used to render text or
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
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.
inclusion/exclusion result See inclusion/exclusion
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
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
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.
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
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.
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
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
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.
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
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
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.
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.
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.
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
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
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.
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
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
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
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.
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
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
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.
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
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
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.
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
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.
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
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
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.
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
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.
value of the equation for the corresponding input
(for example,[0] = 0, [1] = 2, [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
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
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.
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
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
managed install An Installer-driven installation
process. Users open an installer package in the
Installer application, which performs all installation
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.
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.
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
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.
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
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
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.
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
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
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.
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
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
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.
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
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 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
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.
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.
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
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.
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.
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
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
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.
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
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
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.
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
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
open source Software that includes freely available
access to source code, redistribution, modification,
and derived works. The full definition is available
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
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
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.
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’
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
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
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.
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
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,
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
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
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
2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved.
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
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.
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.
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,
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
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.
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
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.
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
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)
pixel depth The number of bits per pixel in a pixel
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.
player See music player.
polyphonic Describes an instrument capable of
playing more than one note simultaneously.
Compare monophonic. See also monotimbral,
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
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
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
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
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
+ bx
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().
2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved.
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
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
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.
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
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
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
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.
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
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
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
2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved.
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
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
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
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
product An application or framework produced by
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.
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
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
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.
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
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
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.
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
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.
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
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
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
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.
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
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
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.
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
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.
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
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
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
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
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.
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
rendering context In OpenGL, a container for state
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
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
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
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.
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
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
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
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.
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
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.
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
routine In Mach, a remote procedure call that
returns a value. A routine can be used for
synchronous or asynchronous operations. See also
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.
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
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
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
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
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.
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
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.
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.
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.
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
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
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.
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
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
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
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.
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
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
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.
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
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.
evaluation. Smart cards can exchange information
with a personal computer through a smart card
SMTP Simple Mail Transfer Protocol. A protocol used
to transfer email between computers, usually over
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
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.
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
2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved.
is made. (2) In AppleTalk protocols, a socket serves
the same purpose as a “port” in IP transport
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
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.
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
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
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
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.
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
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
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
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
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.
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
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
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.
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
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.
surrogates Values that allow additional characters
to be mapped to the Unicode 16-bit character set.
synchronization See keyboard and font
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
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
syntax The arrangement of words in an AppleScript
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.
syntax formatting In Xcode, formatting that uses
different fonts and colors to identify particular
elements in a source code file, such as keywords and
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
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
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,
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.
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
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.
sequence. Sequences that have been temporally
compressed typically contain key frames at regular
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
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
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
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,
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.
text macro In Xcode, a menu item or keystroke that
lets you insert common constructs and blocks of
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
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
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.
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
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.
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
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
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
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.
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
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
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
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.
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
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.
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
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
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
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.
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
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
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.
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
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.
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
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.
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
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
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.
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
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
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
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.
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
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
waveform The shape of a signal when visualized
as a graph showing its variation in amplitude over
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.
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
web service A network-based repository of
processes or tasks that can be used by applications
to access data or execute operations across disparate
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
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.
describing the memory prepares the memory for I/O
(which happens when its prepare method is
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
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
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.
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
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.
Document Revision History
This table describes the changes to OS X Glossary .
Changed occurrences of "iOS" to "iOS".
New document that explains OS X terms as of OS X v10.6.
2010-07-09 | Copyright © 2010 Apple Inc. All Rights Reserved.
Apple Inc.
Copyright © 2010 Apple Inc.
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