GEO1_PK1981 identifies the household's province within Pakistan in 1981. Provinces are the first level administrative units of the country. A GIS map (in shapefile format), corresponding to GEO1_PK1981 can be downloaded from the GIS Boundary files page in the IPUMS International web site.
The full set of geography variables for Pakistan can be found in the IPUMS International Geography variables list. For cross-national geographic analysis on the first and second major administrative level of any country refer to GEOLEV1, and GEOLEV2. More information on IPUMS-International geography can be found here.