Identified the set of Census Bureau census tract definitions (boundaries) that were used to code the census tract in Census Tract 1970/80/90 [110] for a specific record.

Allows for changes in census tracts over time. The census tract definition used to code the case must be recorded so that data are correctly grouped and analyzed. If the coding system were not recorded, the census codes would have to be converted or recoded every time the census tracts were changed.

0	Not tracted
1	1970 Census Tract Definitions
2	1980 Census Tract Definitions
3	1990 Census Tract Definitions
Blank	Census Tract 1970/80/90 not coded

Clarification of NPCR Required Status
Census-1990 data items:	Census-2000 data items:
Census Tract  1970/80/90  [110]	Census Tract  2000  [130]
Census Tr Cert 1970/80/90  [364]	Census Tr Certainty 2000  [365]
Census Tract  Cod Sys--1970/80/90 [120]

Information on census tract, census tract certainty, and census tract coding system is required. For tumors diagnosed in or after 2003, Census Tract  2000  [130] and Census Tr Certainty 2000  [365] (Census-2000 data items) are required. For tumors diagnosed in or before 2002, the requirement can be met by collecting either the Census-1990 data items [110, 364, 120] or the Census-2000 data items, although the Census-2000 data items [130 and 365] are recommended for tumors diagnosed in 1998 through 2002.