I've seen one or two weird things in Phase V backward compatibility in the past, but for the most part, it works just fine. In a previous job, we reluctantly had to use Phase V on Alpha VMS. I never saw any problems with compatibility with Phase IV but despite numerous patches, there were reliability issues (and to a lesser extent performance issues) that never quite went away until the application requiring Phase V was withdrawn and we were able to "upgrade" to Phase IV again :-) Regards, Peter Coghlan.