Apologies ...I haven't been clear....And many thanks for your sympathy, believe me I deserve it.

I am, only interested in Windows NT version 4 server and Windows 2000 server. It’s never likely to be a workstation, and all the remaining flavours can be eliminated. This will help me to determine whether I should recurs into folders and sub folder while removing permission (ACL), or whether I should just instruct Perl (...Win32::Perms) to recurs while modifying the ACLs, that's basically it. It is just my way of enforcing inheretance of permission on folders and sub folders. I have no problems with modifying the ACLs regardless of the OS, I basically instruct the script to recurs in any case. But knowing exactly (beyond any doubt) the type of the OS will make things easier and the code more elegant....

Thanks for listening again.