Don't worry about such issues, VFP is not multithreaded yet. And even if it were, as long as your function doesn't use global variables, everything would be safe (because each thread would have its own copy of the function, ie local variables). Almost obvious, any table used by this function should be locked while used, if VFP were multithreaded. Since it's not, it doesn't matter.

But I guess you would have a real problem if more than one instance of your app run in the same time.

Vlad