I'm not sure I understand what you're asking for correctly. UCS works just like an Active Directory. Each user account has fields for a first name, a last name and a login (UID). How each of those fields are displayed to the user depends on the application in question. For example, if you're using the Zarafa Webmail application and want to share a folder with another user then Zarafa will present you with all three attributes making looking up users a breeze. On Windows you can look up domain users via their name, too, not just via their login. On the other hand assigning file and directory permissions on Linux requires you use the login – you cannot change that.