TIGER/Line(TM) Files, 1992 Chapter 2: Version Code and Record Identification Numbers Version Code Identification The version code is a numeric code that uniquely identifies a TIGER/Line(TM) record with a specific release version of the TIGER/Line(TM) files. All record types have a 4- character field for the version code. Codes: Version Code The Census Bureau is reserving all version codes from "0000" through "5000." The Census Bureau reserves these numbers for future TIGER/Line(TM) file releases. The version code for the 1992 TIGER/Line files, is "0005." The version codes for earlier releases of the TIGER/Line files are as follows: TIGER/Line(TM) Precensus File, 1990 "0000" TIGER/Line(TM) Initial Voting District Codes File, 1990 "0002" 1990 Census TIGER/Line file "0003" TIGER/Line Identification Number (TLID) Identification The 1992 TIGER/Line files use a 4-character version number and a permanent 10-digit TIGER/Line(TM) record identification number (TLID) to uniquely identify a complete chain for the Nation. Codes: TLID The 10-digit TLID will not exceed the value 231-1 (2147483647) and will represent the same complete chain in all versions of this file, beginning with the TIGER/Line(TM) Precensus Files, 1990. Topological changes to the complete chain will cause the TLID's to change. For instance, when updates split an existing complete chain, each of the new parts receives a new TLID and the old TLID is not reused. See the section on User Defined Changes to the TIGER/Line(TM) Files below. Record Type R contains the range of unique complete chain record numbers assigned to a census file in a nationwide scheme. Record Type R has the lowest (minimum), and the highest (maximum) record numbers for the range. Permanent record numbers are assigned within each partition of the Census TIGER data base. Numbers are assigned to complete chains beginning at the minimum and increasing the current value until the current value reaches the maximum. Record Locations: TLID The TLID field appears in columns 6 through 15 of the following record types: Record Type 1 Record Type 4 Record Type 2 Record Type 6 Record Type 3 Record Type I Record Linkages: TLID The TLID field provides a key for linking records containing primary attributes describing the complete chain or the geographic entity codes associated with the left and right side of the complete chain (see Figure 1-2, TIGER/Line(TM) File Record Linkages). Record Type I contains the key fields required to link TLID and the GT- polygon identification fields CENID and POLYID. Sort Sequence: TLID Each record type is a separate file. The records in each record type do not have an overall sort sequence. Data users may wish to sort the file by TLID in order to facilitate record linkages. User Defined Changes to the 1992 TIGER/Line Files TLID as a Standard Identification Number Users should store the record number and the version number associated with each complete chain in their local systems to ensure their ability to match records with later versions of the TIGER/Line(TM) files. The record and version numbers of each complete chain provide an important link to the corresponding complete chain in the Census Bureau's TIGER data base. This key will allow users to transfer new information from later Census Bureau TIGER/Line(TM) releases into their data base and to provide readily used updates to the Census Bureau from their data base should they wish to do so. Feature Changes Users should assign a new record number (TLID) and a version number with a value greater than 5,000 to each new complete chain they create in order to avoid duplicating a Census Bureau-assigned record number that may appear elsewhere in the national file. Users should create a new record for each new complete chain, including those formed when a new intersection splits an existing complete chain. If a complete chain has changed feature identifiers, attributes, and/or coordinate positions without creating new complete chains, it is a modified complete chain and does not need a new TLID. Users may wish to mark these changes as well; if they do so, the Census Bureau will use this information to identify changes more quickly and accurately. Users should assign a version code equal to 4,999 for all deleted complete chain and landmark records. This version code will allow the Census Bureau to positively identify all user deletions. Users may assign or reassign polygon and landmark identification numbers in any manner that uniquely identifies each within a file. The Census Bureau's Geography Division is formulating data requirements and standards for data exchange, as of the release date for the 1992 TIGER/Line files. Data users willing to contribute files as part of the data exchange program should contact Charles Dingman, Chief, Geographic Base Development Branch, Geography Division, Bureau of the Census, Washington, DC 20233-7400. His telephone number is (301) 763-4664 and his Internet address is "cdingman@isdres.er.usgs.gov." TIGER/Line(TM) Polygon Identification Numbers (CENID and POLYID) Identification The Census Bureau uses two fields to uniquely identify GT-polygons. CENID: The CENID is an internal Census Bureau identifier used to uniquely number the GT-polygons. CENID's are the FIPS State and county codes for the county "partitions" (files) that form the national Census TIGER data base. Since the partitions may include more than one tabulation county, the 1992 TIGER/Line files based on 1990 tabulation counties may contain multiple CENID's. POLYID: The polygon identification number (POLYID) is a temporary number assigned to every polygon in the Census TIGER data base. Although this number is part of the Census TIGER data base design, it is a dynamic number and can change between versions of the TIGER/Line(TM) files. The Census TIGER data base does not contain permanent GT-polygon identifiers as it does for complete chains. POLYID is unique only within CENID; in cases where a tiger/Line(TM) file contains more than one CENID, the POLYID may not be unique within that file. Codes: CENID and POLYID CENID: The CENID is a 5-character numeric code with a value that is a combined FIPS State and county code. Record Type R contains a list of all valid CENID's used in each county TIGER/Line file. POLYID: The POLYID code is an integer identification number, without leading zeros, applied to each GT-polygon. The POLYID with a value of 1 refers to the "universal polygon," the polygon that refers to all space outside a county coverage area and is excluded from Record Types A, F, G, I, and P. The range of POLYID numbers in a county file may contain gaps or skipped numbers resulting from the use of one census file (CENID) for more than one TIGER/Line county file. Either the CENIDL and POLYIDL, or CENIDR and POLYIDR fields in Record Type I will have a blank value where the complete chain is a county boundary and the GT-polygon is outside of the county/file (see the discussion below on record linkage). Record Locations: CENID and POLYID The CENID and POLYID fields appear in the following record types: Record Type 8 Records exist only for area landmark GT-polygons Record Type A Records exist for all GT-polygons Record Type P Records exist for all GT-polygons Record Type F Records exist only for GT-polygons with corrected 1990 codes Record Type G Records appear only for GT-polygons with entity code changes since January 1, 1990 Record Type I Contains left and right side CENID's and POLYID's associated with each complete chain.Record Type R Contains only CENID.Record Type R lists the minimum and maximum possible TLID's, and the highest TLID from each census file (CENID) used to generate the current version of the TIGER/Line(TM) files. Record Linkages: CENID and POLYID The 1992 TIGER/Line files use both the CENID and POLYID fields to link all of the polygon record types together (Record Types A, P, F, and G) to link the GT-polygons to the associated complete chains, and to link area landmarks to GT-polygons (see Figure 1-2, TIGER/Line(TM) Record Linkages). The CENID and POLYID fields link the 1990 geographic area codes in Record Type A to Record Type P containing the coordinates for an internal point in the GT-polygon. The 1992 TIGER/Line files include a Record Type A record for each Record Type P record. Record Type F, which contains corrected 1990 geographic area codes, and Record Type G, which reflects current geography, exist only for GT-polygons with changes to the uncorrected 1990 geography. In order to create a list of all current GT-polygons belonging to a place, search Record Type A for the relevant GT-polygon records and extract those with the matching place code. Add or subtract GT-polygons from Record Type G with matching place codes. Note that Record Type G contains all changes to the uncorrected 1990 codes including those contained in Record Type F, unless further changes have since changed the codes in Record Type F. Record Type I provides a link between the GT-polygon records and the record types containing complete chain attributes (Record Types 1, 2, 3, 4, and 6). Each Record Type I record identifies a complete chain by TLID with a left and right side GT-polygon. Here CENIDL and POLYIDL contain the CENID and POLYID numbers for the GT-polygon on the left side of the line. Likewise, CENIDR and POLYIDR contain the CENID and POLYID numbers for the GT-polygon on the right side of the line. There is a Record Type I record for each record in Record Type 1. All CENID and POLYID numbers appear in Record Type I. To find all of the complete chains that form the boundary of a specific GT-polygon, search Record Type I for a match with either the left or right CENID and POLYID. Where left and right CENID and POLYID numbers are the same, the complete chain is internal to the GT-polygon (e.g., a dead end street). Record Type 8 provides a link between the GT-polygons and the landmark feature records. See the section below on landmark identification numbers. Sort Sequence: CENID and POLYID The POLYID numbers appear in sequential order by CENID in Record Types A, F, G, and P. TIGER/Line(TM) Landmark Identification Numbers (LAND) Identification The landmark feature identification number (LAND) is a 10-digit number that uniquely identifies both point and area land marks within each county file. LAND is not a permanent number; the Census Bureau assigns the LAND's each time a new version of the TIGER/Line(TM) files are produced. In rare situations, Record Type 7 may list the same LAND number more than once if the landmark has more than one feature name. Each name appears as a separate data record in Record Type 7. These data records describe the same landmark and have the same LAND. Overlapping landmarks e.g., a pond located in a park, also assign more than one name to a GT-polygon. However, overlapping landmarks are separate features with different LAND's. Codes: LAND The LAND is an integer number that does not contain leading zeros. It is assigned during the extraction of the data and is not a permanent number. There may be gaps in the sequence of the LAND's in Record Type 7 because of the way this information is extracted. Record Locations: LAND The LAND field appears in the following record types: Record Type 7 Landmark attributes Record Type 8 Linkage record containing both the LAND and CENID and POLYID fields. Record Linkages: LAND Record Type 8 links each area landmark's LAND with a CENID-POLYID. Each area landmark will have one or more Record Type 8 records that together identify all of the GT-polygons that make up the landmark. Sort Sequence: LAND Record Type 7 and 8 contain records sorted in ascending order by LAND. In Record Type 8, each LAND is repeated for each GT-polygon covered by the area landmark.