SCHEMA.DBF tells you what files and fields are available to you.  

DETAIL.EXE contains the files for the information that changes in a format most 
databases are able to recognize.  

Typically you would make a file of unique reference numbers for the
subset of interest and then use this file to extract the information 
from all of the other files in detail.exe.  For example, if your are 
interested in a particular state then go to the countyd.dbf file and build 
a file of reference numbers where statecd is equal to the state of your 
choice (and select the nonblank primary flag, or primeflg <> ' '--this eliminates the
duplicates that could occur since one property can be in many counties). 
You may also want to filter out properties that are not listed and have
for example a pending or removed status.  If you want only listed properties 
make sure you select propmain.certcd='LI' only (the complete list of code and decodes 
is in certm.certcd).  Now you have a file of unique reference numbers available that 
allows you to extract attributes from all the related one to many files joined on the
basis of the reference number such as apcritd.dbf (applicable criteria)
and archtectd.dbf (architect).  All fields are fixed length. 


MASTER.EXE contains the dbf files for the static information--codes and 
decodes to use in deciphering the detail.exe data files.

Take what you want and throw the rest away.  

GIS users can get Arc Info and Map Info files from Distribution.zip or make them from 
the MS Access subset, spatial.mdb.  GIS files contain listed properties only
 

Database Manager
National Register of Historic Places