JCP,

>Of course was is my first thought, and my plan B. But the nature of what they do requires them to move the tables around. Another file would be easy to loose and tracking it in a database without some kind of unique id would be problematic. Files from different states may be in different directories with the same file name.

I suppose you can't force the issue of embedding an ID into the filename?

>This is potential problem even using the DBF header. If anyone copies the file or modifies structure, my key is lost and linking it up again could really be a problem. I need to determine which is more likely, loosing a separate file or losing my little key in the header.

And I suppose you can't add an ID field to each table that is used only by you to contain the tracking ID -- then document that field as "untouchable"? You could put the ID into that field in every record if necessary, to insure that you can find it even if people delete some records.