There is a specific workflow that requires there be no more than one version (i.e., #1, and only a #1) for files in a specific Perforce path. Updating these files with a version #2 is not allowed.
Is there a way to prevent Perforce from allowing a #2 checkin for a Perforce tree?
Locking the entire tree is not an option, since users are free to check-in new files, just not update existing ones.