U

universal group

A group that can contain members from any domain and can be granted permissions to resources in any domain in the current domain forest.

update sequence number

A type of identifier that is used to control replication between domain controllers in Windows 2000 and Windows Server 2003.

UPN

See user principal name.

user principal name

A logon name type of a user on a Windows 2000 or Windows Server 2003 network. The user principal name consists of the user object name used in Active Directory, followed by the at symbol (@) and then, typically, the Domain Name System parent domain. For example, JeffSmith in the Fabrikam.com domain tree might have the user principal name jeffsmith@fabrikam.com.

USN

See update sequence number.