U
UA User Agent
UAE Unrecoverable Application error
UART Universal Asynchronous Receiver/Transmitter
UBR Undefined Bit Rate
UBS Unit Backspace
UCB Unit Control Block
UCR Undercolor removal
UCS Universal Character Set
UCSB Universal Character Set Buffer
UCW Unit Control Word
UDP User Datagram Protocol
UI User Interface
UID User ID
UMB Upper Memory Block
UNC Universal Naming Convention
UNC Universal Network Convention
UPC Universal Product Code
UPS Uninterruptible Power Supply
UPSI User Program Switch Indicator
UR Unit Record
URL Uniform Resource Locator
US Unit Separator
USART Universal Synchronous/Asynchronous Receiver/Transmitter
USENET USEr NETwork
USM UnSharp Masking
USRT Universal Synchronous Receiver/Transmitter
USV Unterbrechungsfreie StromVersorgung
UTP Unshielded Twisted Pair
UUCP Unix-to-Unix Copy Program
