There are four files for metadata.

bg90.txt - is a metadata file for the block group polygon coverages for
           all of the states (Al, GA, SC, NC, TN, VA, and WV).

stf3a.txt - is a general description of the Summary File 3.

stf3a_ta.txt - is a description of the STF3A Tables.

stf3a_dd.txt - is a data dictionary for the STF3A items.


STF3A INFO files can be related to the Block Group coverages 
with the redefined item STCNTRBG.