Actually, your response has me thinking of a better solution. The admin
makes the directory where the workbook is read only. That way, all users
could only open the original read only file, even if a user does a local
(his own machine) save as, because he cannot write to that directory.
Hopefully, they do not pass around edited data files to each other,
calling them the bona fide file. The original author of the file gets
items placed into that directory, meant for read only access, via the
Administrator.