Thank you for your reply.

No, this is the only program that knows about the data file. I have read about this in the various books and online help and verified this.

I have another idea, though:

I wonder if it's possible for Perl or the Web server to occasionally have a new instance of the same Perl script inherit the locks of a previous instance of the script. I got this idea by reading about how forking inherits locks.

For example, let's say 10 people submit the same form at the same time. Each of the 10 submissions starts a new instance of the same Perl script. The Perl script uses flock to lock a secondary file. Is it possible for Perl to occasionally decide that one instance of the script should inherit the locks of another? If so, then the locking has been defeated.

Richard