I found a Users Guide for the Numident that was compiled by RAND Corporation in a Google search. Clicking on the link downloads a 651 page manual. The Numident description is on page 406 and details of data fields follow. Here is what Google provided as an address that pops up a window about downloading or opening with Adobe Acrobat the document file itself. First below I provide the tinyurl.com version and then the complete version from Google.
http://tinyurl.com/mcsvvzchttp://www.google.it/url?sa=t&rct=j&q=&esrc=s&am...