I was looking at the help on this in VFP and the way it was stated for "BIT VALUE (additive) for 4 is as follows

*** Stright from VFP 9 Help on SET TABLEVALIDATE***
Suppress "File is in use (Error 3)" if table header cannot be locked when opening the table. Requires setting the first bit to validate record count when opening a table.

Note
When opening a table, the USE command attempts to lock the table header only once. If the header is locked, Visual FoxPro performs a strict header check, similar to SET TABLEVALIDATE set to 1. Otherwise, Visual FoxPro suppresses the "File is in use" error and performs a header check in the manner of versions prior to Visual FoxPro 8.0.


So, I was under the impression that any version under vfp 8 has some kind of header checking and that if I set it to 0, that there would be no header checking at all. That's why we went with 4, to make sure it work like it did before.