Statistics Canada Block-Face Data File User Guide

1991 BLOCK-FACE DATA FILE

TABLE OF CONTENTS

1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Reference Date . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2. DATA QUALITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Lineage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Positional Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Attribute Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Logical Consistency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Completeness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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3. TECHNICAL SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Record Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Field Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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4. GLOSSARY OF TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

5. ADDITIONAL SERVICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

TABLES

Table 1. Block-face Coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 2. Number of Block-Face Records per CMA/CA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 3. Incomplete Block-face Linkages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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SUPPLEMENT

EA Linkage Errors on the 1991 Geographic Attribute Data Base

ARC/INFO® is a registered trademark of Environmental Systems Research Institute Inc.

1. INTRODUCTION

This user guide provides information on the coverage, content and data quality of the 1991 Block-face Data File. It also includes a section on technical specifications and a glossary of terms. A supplementary document appears at the end of this user guide. Its purpose is to show the EA linkage errors on the 1991 Geographic Attribute Data Base, which is one of the sources used in generating the Block-face Data File.

The Block-face Data File provides attribute information for the smallest geographic entity available from Statistics

Canada, namely, the block-face.

Coverage

Block-faces are available where there is Street Network File (SNF) coverage, that is, for large urban centres containing at least one municipality with a population of 50,000 or more. The Block-face Data File is available for 25 census metropolitan areas (CMA) and 19 census agglomerations (CA). In some cases, only portions of CMAs/CAs are covered by

SNF; thus some urban centres may be only partially covered by the Block-face Data File (Table 1).

Content

The block-face attribute information includes street names (including street types and direction), address ranges, geographic codes, block-face representative points (or in some cases, EA representative points), and 1991 population and dwelling counts.

Table 2 provides the total number of block-face records for each CMA/CA.

Reference Date

All census data reflect the census reference date of June 4, 1991. There is also a Geographic Reference Date for the geographic framework that supports the census. This date is earlier than the census reference date in order to give

Statistics Canada enough time before Census Day to process the necessary boundary and name changes. For the 1991

Census, the Geographic Reference Date is January 1, 1991, provided that the information on any changes was received by Statistics Canada from provincial or territorial authorities by March 1, 1991.

The block-face attributes and linkages to the standard geographic areas are obtained from four separate sources: the

Street Network Files (SNF), the EA Digital Boundary File, the Geographic Attribute Data Base (GADB), and the

1991 Census Data Base. Each source has its own inherent reference date, as follows:

- Street Network Files: vary between June 1986 and December 1991 for the network information, and between

June 1986 and February 1991 for the address information.

- EA Digital Boundary File: January 1, 1991. The EAs that were split on Census Day due to dwelling increases are included in the boundary file.

- Geographic Attribute Data Base: January 1, 1991 for the geographic attributes and linkages, and June 4,

1991 for the population and dwelling counts.

- 1991 Census Data Base: June 4, 1991.

Limitations

Some address ranges are assigned to FED, EA and CT codes that are set to zero (0). This occurs because their respective block-face representative points fall outside these geographic areas.

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Approximately 93% of the population and dwelling counts are linked to block-face representative points; the remaining

7% are linked to EA representative points.

Despite the linkage to the 1991 Census, the Street Network Files have not been updated using the information collected during the 1991 Census field operations. Consequently, users should be aware that some streets and attributes have not been added to the Street Network Files.

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This list denotes which CMAs and CAs are covered by block-faces, and whether the urban centre is wholly or partially covered by the Block-face Data File. A blank indicates that the entire CMA or CA is covered by the Block-face Data

File.

Brantford

Calgary

Chicoutimi - Jonquière

Edmonton

Québec partial partial Regina partial partial Saint-Jérôme partial

Guelph

Halifax

Hamilton

Kamloops

Kelowna

Kingston

Sarnia - Clearwater

Sault Ste. Marie

St. Catharines - Niagara partial partial

Lethbridge

London

Matsqui

Moncton

Montréal

Sudbury

Thunder partial partial partial

Toronto partial

Trois-Rivières partial

Oshawa

Ottawa - Hull

Victoria

Windsor

Winnipeg

Peterborough partial Woodstock partial

Note: The five urban centres denoted in bold text are covered by provincial census tracts (PCT). The remaining centres are covered by census tracts (CT).

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Number of Block-Face Records per CMA/CA

Belleville

Brantford

Calgary

Edmonton

Fredericton

Guelph

Halifax

Hamilton

Kamloops

Kelowna

Kingston

Kitchener

Lethbridge

London

Matsqui

Moncton

Montréal

Oshawa

Ottawa - Hull

Peterborough

4,814

28,108

Sarnia - Clearwater

Sault Ste. Marie

7,102 St. Catharines - Niagara

4,471 John's

47,102 Winnipeg

6,312

28,381

3,507

11,173

1,519

5,647

5,648

10,141

5,071

3,672

30,644

4,444

1,771

5,205

7,254

112,186

6,512

84,179

18,668

11,576

33,270

1,877

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2. DATA QUALITY

The purpose of a data quality report is to provide detailed information for users to evaluate the suitability of the data or product for a particular use. Five fundamental components of a data quality statement are: lineage, positional accuracy, attribute accuracy, logical consistency and completeness.

Since the data for the Block-face Data File were extracted from four distinct files, users should consult the detailed data quality statements for each of the following source files:

- Street Network File, User Guide (AMF Format).

- 1991 Digital Boundary Files, User Guide.

- 1991 Geographic Attribute Data Base, Data Quality Statement.

- 1991 Census Data Base.

Lineage

Lineage includes descriptions of the source material from which the data were derived and the methods of derivation, including the dates of the source material and all transformations involved in producing the final digital files or map products.

Source Information

The Block-face Data File was derived from the following source files:

1. The Street Network Files (AMF Format) provided the street names (including street types and direction), odd and even address ranges, and the UTM zone number/coordinates of the block-face representative points within the individual CMAs and CAs. The reference date for the network information varies between June 1986 and December

1991, and between June 1986 and February 1991 for the address information.

2. The 1991 EA Digital Boundary File provided the province, federal electoral district (FED) and enumeration area

(EA) links to the streets and street attributes. The geographic reference date is January 1, 1991. The EAs that were split on Census Day due to dwelling increases are included in the boundary file.

UTM zone number/coordinates of the EA representative points. The reference date is January 1, 1991.

Method of Derivation

Various SAS computer programs (IBM mainframe-based) were used to extract, compile and verify the information.

The first program used the Street Network Files to extract the street attribute information and the block-face representative points. An ARC/INFO® point-in-polygon algorithm was used on the EA Digital Boundary File to determine which SNF block-face representative points fell within the individual EAs; this in turn provided the province, FED and EA linkages to the block-face representative points.

The extracted information from the SNF and EA Digital Boundary File was then merged, which resulted in the linkage of province, FED and EA codes to the street attributes.

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The Geographic Attribute Data Base supplied the other necessary linkages and names/codes for the standard geographic areas, as well as the EA representative points.

An in-house STATPAK retrieval program extracted the population and dwelling counts from the 1991 Census Data

Base. The counts were then linked to either block-face or EA representative points.

Block-face representative points are computed within all Street Network Files along addressable streets and addressable sections of highways. The representative point is located at the mid-point of the block-face, set back a perpendicular distance of 22 metres from the street centre line. EA representative points within Street Network Files are located by an automated method using ARC/INFO® GIS software, which locates the point suitable for label or symbol placement in each polygon.

Various automated and manual methodologies were used to link the households (and thus the population and dwelling counts) to block-faces and EAs. Approximately 81% of the households were directly linked to addresses by census enumerators in the field. An automated Address Register program then linked these addresses to the block-face. A further 12% of the households involved a manual and subjective process; addresses were linked to block-faces by

Statistics Canada staff who rationalized the information by examining census collection reference material (such as

Visitation Records, EA collection maps and SNF street indexes). The remaining 7% of the households were linked to

EAs because overseas population and other households could not be specifically linked to block-faces due to insufficient or missing address information, or to missing streets on the Street Network Files.

Positional Accuracy

Positional accuracy is the difference between the "true" position of a feature in the real world and the "estimated" position stored in the digital file or other product.

Due to the computation method, block-face representative points may not be unique. For example, perpendicular blockfaces of equal length may be assigned representative points having the same coordinate values. In addition, there are

130 block-face representative points -- although having the correct CD/CSD code -- that fall outside the CD/CSD in which they should be located. This occurs because of the 22 metre rule to locate the points.

Attribute Accuracy

Attribute accuracy refers to the accuracy of the non-positional information attached to each feature.

The Block-face Data File reflects the accuracy of the Street Network Files from which street attributes were extracted, the 1991 Geographic Attribute Data Base from which the names and codes of geographic areas were extracted, and the

1991 Census Data Base from which population and dwelling counts were extracted. No edits were performed on the extracted data from these source files.

For further information on the accuracy of the population and dwelling counts at the EA level, please refer to the data quality statement in Supplementary Tables, Population and Dwelling Counts, Enumeration Areas (Reference D9133, pp. 4-7). The accuracy of population and dwelling counts at the block-face level is related to the methodology used to link the households to block-faces.

For the 130 block-face representative points that fall outside the CD/CSD in which they should be located, the FED, EA and CT codes and population and dwelling counts are set to zero. Table 3 shows the number of incomplete block-face linkages for the affected CMAs and CAs. Population and dwelling counts are also

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Incomplete Block-face Linkages

CMA/CA Number

Ottawa - Hull

St. Catharines - Niagara

______

TOTAL 130

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set to zero when two block-face representative points have the same coordinate values. In these cases, the aggregated counts for the two block-faces are assigned to one block-face; the other block-face count is set to zero.

Logical Consistency

Logical consistency describes the fidelity of relationships encoded in the data structure of the digital spatial data (i.e. how well elements of the data structure follow the rules imposed on them).

A post census verification confirmed that the PROV/FED/EA linkages were consistent with the Geographic Attribute

Data Base and the extracted information from the EA Digital Boundary File.

All EA representative points are guaranteed by an ARC/INFO® topology check to fall within the appropriate EA.

Completeness

Completeness expresses the degree to which geographic entities (features) are captured according to the data capture specifications. It also includes information about selection criteria, definitions used and other relevant mapping rules.

The Block-face Data File does not provide information for those parts of CMAs or CAs outside Street Network File coverage. The file contains street attributes, codes and linkages to standard geographic areas, and population and dwelling counts for 769,066 block-face records (including unpopulated block-faces) for the CMAs/CAs in SNF coverage.

The file also contains 11,757 EA records for the population and dwelling counts that could not be linked to block-faces.

Users should also be aware that some street names and address ranges are unidentifed or unavailable. In addition, the

Street Network Files have not been updated using the information gathered during the 1991 Census field operations.

Consequently, some streets and attributes have not been added to the Street Network Files.

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3. TECHNICAL SPECIFICATIONS

This section describes the record layout and field descriptions of the 1991 Block-face Data File.

Record Layout

The following record layout provides an overview of the 18 fields in the Block-face Data File. It contains the field number, size of field, field position, field type (numeric or alphanumeric) and description.

Field Size Position Type Description

1 20

2 2

3 2

4 5

5 5

6 2

7

8

6

7

9 1

10 4

35-36

37-42

43-49

50

N

N

N

N

UTM zone number of representative point

UTM x-coordinate of representative point

UTM y-coordinate of representative point

Population/dwelling linkage flag

11 4

12 2

13

14

3

3

15

16

17

18

2

3

3

7.2

59-60

61-63

64-66

67-68

69-71

72-74

75-81

N

N

N

N

N

N

N

Province/territory code

Federal electoral district code

Enumeration area code

Census division code

Census subdivision code

Census metropolitan area/census agglomeration code

Census tract/provincial census tract name

Field Descriptions

Field 1: Street Name

Street names are generally based on municipal documents provided to the Street Network File program.

Users should note the following coding rules:

- names are truncated (at the end) if they exceed the maximum field size of 20 characters.

- formats of the word "Saint" and "Sainte" are abbreviated as ST and STE.

- most numeric streets are coded using the number rather than the alphabetic spelling (for example, First Avenue is 1 AV).

- most articles are coded at the end of the street name (for example, The Queensway becomes QUEENSWAY,

THE, and De l'Eglise becomes EGLISE, DE L').

- all unidentified street names are coded using 3-digit numbers prefixed by a "Z" (e.g. Z001).

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Field 2: Street Type

Street type is a two-letter code that identifies the different types of addressable streets.

Code Type Code Type

AL Alley / Allée LK Link

AU Lane

BV Promenade

CA Carré PR Park / Parc

CL Circle / Cercle PY Parkway

CN Road

CR

CT

Crescent / Croissant

Court / Cour

RI

RO

Rise

Route

HL Hill TR Terrace / Terrasse

Field 3: Street Direction

Street direction is a one- or two-letter code that denotes the location of the street relative to a pre-defined origin (for example, Sherbrooke St. West). The street direction is included only if it is part of the street name. The direction should not be misconstrued as being the geographic direction of the street.

N

S

North / Nord

South / Sud

E East / Est

NE North-East / Nord-Est

SE South-East / Sud-Est

Field 4: Address From

"Address from" is a number representing the low civic address of the block-face. If an addressable street follows a CSD boundary, the address is coded for only the side of the street contained within the CSD. An unknown address is coded by the symbol "_______".

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Field 5: Address To

"Address to" is a number representing the high civic address of the block-face. If an addressable street follows a CSD boundary, the address is coded for only the side of the street contained within the CSD. An unknown address is coded by the symbol "_______".

Field 6: UTM Zone of Representative Point

This field denotes the UTM zone in which the block-face or EA representative point is located. The field should be used in conjunction with the x,y coordinates of the representative points.

Atlantic Newfoundland

Prince Edward Island

Nova Scotia

New Brunswick

10

11

12

13

Quebec

Ontario

Prairies

Quebec

Ontario

Manitoba

Saskatchewan

24

35

46

47

British Columbia

Territories

Alberta

British Columbia

Yukon Territory

Northwest Territories

48

59

60

61

Sixteen UTM zones cover Canada, bearing numbers 7 to 22 from west to east.

19 to 22

20

19 to 21

19 and 20

17 to 21

15 to 18

14 and 15

12 to 14

11 and 12

7 to 11

7 to 10

8 to 21

A block-face representative point is located at the mid-point of the block-face, set back a perpendicular distance of 22 metres from the street centre line. An EA representative point (within Street Network File coverage) is generated by an automated method using ARC/INFO

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GIS software, which locates the point suitable for label or symbol placement in each polygon.

Field 7: UTM x-Coordinate of Representative Point

The UTM x-coordinate (easting) of the block-face or EA representative point is a 6-digit value in metres.

Eastings are measured from the central meridian (called the 500,000-metre line) for each zone. The points west of the central meridian have easting values of less than 500,000; points east of the central meridian have values greater than

500,000. Eastings are all greater than 0 and less than 1,000,000.

Field 8: UTM y-Coordinate of Representative Point

The UTM y-coordinate (northing) of the block-face or EA representative point is a 7-digit value in metres.

Northings are measured by their distance in metres from the equator. Because Canada's southernmost point is about

4,620,000 metres from the equator, all points in Canada have a northing value greater than 4,620,000.

Field 9: Population/Dwelling Linkage Flag

The linkage "flag" is a 1-digit code that denotes whether the population and dwelling counts are linked to block-face or

EA representative points.

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This distinction is made because overseas population and other households could not be specifically linked to block-face representative points due to insufficient or missing address information, or to missing streets on the Street Network

Files. In these cases, the population and dwelling counts are linked to EA representative points instead.

Field 10: Population Count

This field contains unrounded 1991 population counts. These counts are assigned to block-face or EA representative points.

Field 11: Dwelling Count

This field contains unrounded 1991 dwelling counts (occupied private dwellings only). These counts are assigned to block-face or EA representative points.

Field 12: Province/Territory Code

The province/territory is designated by a 2-digit code that is based on the Standard Geographical Classification (SGC).

The code is assigned from east to west. The first digit represents the region of Canada to which the province/territory belongs; the second digit denotes one of the ten provinces and two territories.

Region Province Code

Prince Edward Island 11

British Columbia British Columbia 59

Field 13: Federal Electoral District (FED) Code

The FED is designated by a 3-digit code. In order to uniquely identify each FED in Canada, the code must be preceded by the 2-digit province code. For example:

12 001

46 009

Annapolis Valley-Hants

Winnipeg North

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Field 14: Enumeration Area (EA) Code

The EA is designated by a 3-digit code. In order to uniquely identify each EA in Canada, the code must be preceded by the 2-digit province code and the 3-digit FED code. For example:

12 009 251

35 009 251

Province 12: Nova Scotia

FED 009: Halifax West

EA: 251

Province 35: Ontario

FED 009: Cambridge

EA: 251

46 009 251 Province 46: Manitoba

FED 009: Winnipeg North

EA: 251

Field 15: Census Division (CD) Code

The CD is designated by a 2-digit code that is based on the Standard Geographical Classification (SGC). In order to uniquely identify each CD in Canada, the code must be preceded by the 2-digit province code. For example:

12 03

24 03

35 15

59 15

Field 16: Census Subdivision (CSD) Code

Digby County

La Côte-de-Gaspé

Peterborough County

Greater Vancouver Regional District

The CSD is designated by a 3-digit code that is based on the Standard Geographical Classification (SGC). In order to uniquely identify each CSD in Canada, the code must be preceded by the 2-digit province code and the 2-digit CD code.

For example:

12 09 021

35 09 021

Halifax

Perth

Field 17: Census Metropolitan Area/Census Agglomeration (CMA/CA) Code

The CMA/CA is designated by a 3-digit code that uniquely identifies each urban centre in Canada. The first digit of the

CMA/CA code uses the second digit of the province code (except in the Territories where the CMA/CA code starts with number 9). If a CMA or CA crosses a provincial boundary, the first digit of the code reflects the province that contains the CMA portion with the higher population (e.g. CMA code 505 for Ottawa - Hull). The second and third digits are assigned in numeric order from 1 to 99 by province.

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For example:

505 35 Ottawa - Hull

Field 18: Census Tract/Provincial Census Tract (CT/PCT) Name

The CT name is a unique 7-digit number (including leading zeros and the decimal point), assigned in ascending order within a CMA or CA. However, CT names may not be unique between CMAs or CAs. The PCT name is also a 7-digit number (including leading zeros and the decimal point), assigned in ascending order within a province.

The Block-face Data File does not make a distinction between CTs and PCTs in the name field. (Refer to Table 1 which indicates the urban centres covered by CTs or PCTs.)

If a CT/PCT is split into two or more parts due to a population increase, the numbers after the decimal point identify the splits. For example:

CT Name in 1986 CT Name in 1991

0400.02

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4. GLOSSARY OF TERMS

The glossary provides an explanation of the terms used in the Block-face Data File. The terms are presented in summary form only. Please refer to the 1991 Census Dictionary (Catalogue 92-301E) for the full definitions.

Block-face (BF). One side of a city street, normally between two consecutive intersections with streets or other features such as rivers and railways. A block-face is generally used for census data aggregation in large urban centres within

Street Network File coverage.

Census Agglomeration (CA). A large urban area, together with adjacent urban and rural areas which have a high degree of economic and social integration with that urban area.

A CA is delineated around an urban area (called the urbanized core and having a population of at least 10,000, based on the previous census). If a CA's urbanized core population falls below 10,000, it is deleted from the CA program.

However, if a CA attains an urbanized core population of at least 100,000, based on the previous census, it becomes a census metropolitan area (CMA).

Census Division (CD). A geographic area established by provincial law which is an intermediate area between the census subdivision and the province (e.g. division, county, regional district, regional municipality).

In Newfoundland, Manitoba, Saskatchewan and Alberta, provincial law does not provide for this administrative area. Therefore, CDs have been created by Statistics Canada in cooperation with these provinces.

Census Metropolitan Area (CMA). A very large urban area, together with adjacent urban and rural areas which have a high degree of economic and social integration with that urban area.

A CMA is delineated around an urban area (called the urbanized core and having a population of at least

100,000, based on the previous census). Once an area becomes a CMA, it is retained in the program even if its population subsequently declines.

Census Subdivision (CSD). A municipality as determined by provincial legislation (such as city, town, village), or its equivalent (e.g. Indian reserve, Indian settlement and unorganized territory).

In Newfoundland, Nova Scotia and British Columbia, other types of CSDs have been created by Statistics

Canada in cooperation with the provinces as equivalents for municipalities.

Census Subdivision Type. The type indicates the municipal status of a census subdivision. CSDs are classified into various types, according to official designations adopted by provincial or federal authorities.

Census Tract (CT). A permanent, small urban neighbourhood-like or rural community-like area established in large urban centres with the help of local specialists interested in urban and social science research.

Census tracts are delineated jointly by a local committee and Statistics Canada. The population must be between 2,500 and 8,000, with a preferred average of 4,000 persons (except for those CTs in central business districts, in other major commercial and industrial zones, or in peripheral rural or urban areas that may have either a lower or higher population). Also, when first delineated or subsequently subdivided, CTs must be as socio-economically homogeneous and compact in shape as possible.

All CMAs and CAs in Canada containing a CSD having a population of 50,000 or more at the previous census are eligible for a census tract program.

Enumeration Area (EA). The geographic area canvassed by one census representative. The number of dwellings in an

EA generally varies between a maximum of 375 in large urban areas to a minimum of 125 in rural areas. An EA always respects higher level geographic areas recognized by the census, and is the smallest unit for which census data are usually available.

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Federal Electoral District (FED). Any place or territorial area entitled to return a member to serve in the House of

Commons. FED legal limits and descriptions are the responsibility of the Chief Electoral Officer, and are usually revised every 10 years after the results of the decennial census.

The 1987 Representation Order is the most current one, and is based on 1981 Census population data.

Geographic Area. An area delineated or employed for the collection, compilation, analysis and dissemination of census data.

Geographic Attribute Data Base. A Statistics Canada relational data base which contains a number of attributes (such as names, codes, population and dwelling counts, land area) for standard geographic areas, and linkages between the geographic areas.

Province. The major political division of Canada. From a statistical point of view, it is a basic unit for which data are tabulated and cross-classified.

Provincial Census Tract (PCT). A permanent, small urban neighbourhood-like or rural community-like area established outside those CMAs and CAs having a census tract program. PCTs encompass populations between 3,000 and

8,000, with a preferred average of 5,000 persons.

Representative Point. Formerly called a centroid, a representative point is a pair of x,y coordinate values that represents a geographic entity for the purpose of assigning aggregate data to that entity.

Standard Geographical Classification (SGC). Statistics Canada's official classification of geographic areas in Canada.

The SGC provides unique numeric identification for three types of geographic areas: provinces/territories; census divisions; and census subdivisions.

The three geographic areas are hierarchically related. CSDs aggregate to CDs, which in turn aggregate to a province or territory. This relationship is reflected in the 7-digit code: 2 digits for provinces/territories, 2 digits for census divisions and 3 digits for census subdivisions.

Street Network File (SNF). Formerly known as the Area Master File (AMF), the Street Network File is a computerreadable file that geographically references the street network and selected other non-street features (such as rivers, lakes, railways and municipal limits). SNFs are generally created for urban centres containing at least one municipality with a population of 50,000 or more at the previous census. These centres are normally in the census tract program.

The SNF contains the names for all street and non-street features. In addition, the intersection (corner) civic address ranges and block-face representative points are available for addressable streets.

Universal Transverse Mercator (UTM). An international grid system that covers the earth's surface between 84 o

N and

80 o

S. The earth is divided into 60 north-south zones, each of which is 6 o

of longitude wide. The zones are numbered from 1 to 60 eastward, beginning at the 180th meridian. A grid system is superimposed on the zones, and separate

Transverse Mercator projections are centred on each zone.

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5. ADDITIONAL SERVICES

In addition to the Regional Reference Centres and depository libraries, Statistics Canada publications may be ordered through your local bookstore or subscription agent. Contact the nearest Regional Reference Centre for a list of Canadian outlets available, or consult the 1991 Census Catalogue (Catalogue 92-302E).

Secondary distributors offer data access and analytical support through a variety of consulting and computer-based services not available at Statistics Canada. The names and addresses of licensed distributors may be obtained from any

Regional Reference Centre.

Statistics Canada provides digital geographic products which allow computer manipulation of geographic data. A customized retrieval service is available for users who wish to define their own geographic area of study. A variety of data retrieval files and services provide flexibility in selecting a geographic base.

A complete description of available digital files and services is documented in the 1991 Census Catalogue (Catalogue

92-302E).

Information concerning Census of Agriculture products and services may be referenced in the 1991 Census of

Agriculture Products and Services (Catalogue 92-303), or by calling toll free 1-800-465-1991.

Users with special data requirements may request post-census survey services. Data are made available on microcomputer diskettes for use with spreadsheet software, or on paper output. For additional information, please contact the nearest Regional Reference Centre.

The Dissemination Division is responsible for CANSIM, Statistics Canada's computerized database network and information retrieval service. Users are provided with access to current and historical statistics in various forms including specialized data manipulation and analysis packages, graphics facilities and a bibliographic search service.

For more information about CANSIM, contact any Regional Reference Centre.

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