XMS - Extended Memory Specification

XNS - Xerox Networking System

XOR - Exclusive-or

XPG - X / open Portability Guide

XPM - X - windows Pixelmaps

XPRM - Xerox Print Resources Manager

XPS - Extended Parallel Server

XRT - Extensions for Real - Time

XSL - Extensible Style Language

XSMD - Extended Storage Module Drive

XSSI - Extended Server Side Includes

XT - X Terminal

XTCLK - External Transmit Clock

XTP - Express Transfer Protocol