>The biggest problem with this approch would be cleaning leftovers after program and PC crashes. With locks created by RLOCK() it's done by file server.
>

Sergey,
It's not really a big deal. < s > We use this semaphore locking scheme in our VFP/Oracle system. In order to clean up leftover crap, we have an SP that is scheduled to run every night. Of course, we can manually run it anytime we want.