This UUID should be created when a user is being registered or when a person document is created.
This UUID could be used to internally identify the user instead of the Full Name, for example in Acces control Lists, Reader and Author fields, Group Documents, etc..
With this UUID could it be possible to change the user Full Name without the need to change ACLs, Reader and Author fields, etc
Thus we could speed-up some process like the rename in the adminp process, because there would no need to search all servers databases to change ACLs, Reader and Author fields, etc.
Of course when viewing a user, for example in an access control list, the full name of the user should be displayed instead of the uuid.
To display the user there would be an internal function to get the current user name from the UUID.