File 43—File Linking Fields (comma delimited). These fields link File 43 with the geographic header. Data dictionary Field name reference Max Data Name size type File Identification FILEID 6 A/N State/U.S. Abbreviation (USPS) STUSAB 2 A Characteristic Iteration CHARITER 3 A/N Characteristic Iteration File Sequence Number CIFSN 2 A/N Logical Record Number LOGRECNO 7 N H2. URBAN AND RURAL [6] (Urban/Rural Update only) Universe: Housing units Total: H0020001 43 9 Urban: H0020002 43 9 Inside urbanized areas H0020003 43 9 Inside urban clusters H0020004 43 9 Rural H0020005 43 9 Not defined for this file H0020006 43 9