Thanks again.

But I found the answer to my question. At the MSDN web site; KB article Q222676 - HOWTO: Tell If a VFP COM DLL is Single-threaded or Multi-threaded. It turns out to be very simple. In Single-threadfed DLL the word "foxwd" exists in the code, and in Multi-thereaded DLL the word "foxwt" exists. Sometimes things are way too easy.