>How would I generate a unique invoice number (sequential) in a multi-user environment, and guarentee no two users get the same number . I know I have to use file locking, but what is the canned procedure.

You have separate table Setup.dbf (two fields Tablename and Counter) with separate records for each table where sequential is needed.

Procedure GetNewId
lParameter cTablename
Select setup
Locate Setup.Tablename=cTablename
if not found()
 return 0
endif
if rlock()=.f.
 return 0
endif
replace Setup.counter with Setup.counter+1
unlock
return Setup.counter