X+V - XHTML+Voice
X3D - eXtensible 3D
XA - eXtended Architecture
XAA - Xfree86 Acceleration Architecture
XACML - eXtensible Access Control Markup Language
XACT - Xante's Accurate Calibration Technology
XAG - XML Accessibility Guidelines
XAML - eXtensible Application Markup Language
XAMS - eXtended Account Managing Software
XAPIA - X.400 Application Programming Interface Association
XBEL - XML Bookmark Exchange Language
XBL - eXtensible Binding Language
XBL - eXtreme spam Blocking List
XBM - X BitMap
XBP - Xbase Parts
XBRL - eXtensible Business Reporting Language
XBSA - X/Open Backup Services API
XCBF - XML Common Biometric Format
xCBL - XML Common Business Library
XCCI - X Common Client Interface
XCEM - eXtensions for Control, Engineering and Manufacturing
XCF - eXperimental Computing Facility
XCG - XDR Clock Generator
XCHS - eXtended Cylinder Head Sectors
XCITE - Xilinx Controlled Impedance TEchnology
XCMOS - eXtended Complementary Metal-Oxide Semiconductor
XCMS - X Color Management System
XCMS - XML Cryptographic Message Syntax
XCOFF - eXtended Common Object File Forma
XCUTS - X Commands and Utilities Test Suite
XDB - XML DataBase
XDE - eXtended Development Experience
XDK - Xbox Development Kit
XDM - X Display Manager
XDMA - Xing Distributed Media Architecture
XDMCP - X Display Manager Control Protocol
XDNL - XML Document Navigation Language
XDP - XML Data Package
XDR - eXternal Data Representation
XDS - X/Open Directory Service
XE - eXecution Environment
XER - XML Encoding Rules
XES - Xerox® Engineering Systems
XET - Xerox Ethernet Tunnel
XFA - XML Forms Architecture
XFCB - eXtended File Control Block
XFDL - eXtensible Forms Description Language
XFE - X Front End
XFML - eXtensible Faceted Metadata Language
XFN - X/open Federated Naming
XFRML - eXtensible Financial Reporting Markup Language
XFS - eXtended File System
XFS - X Font Server
XFTAS - X-Force™ Threat Analysis Service
XG - eXtended General
XGA - eXtended Graphics Adapter
XGA - eXtended Graphics Array
XHTML - eXtended HyperText Markup Language
XI - XML Integrator
XID - eXchange ID
XIE - X Image Extension
XIO - XDR Input/Output cell
XIOS - eXtended Input/Output System
XIP - eXecute In Place
XIS - eXtensible Information Server
XKISS - XML Key Information Service Specification
XKMS - XML Key Management Specification
XKRSS - XML Key Registration Service Specification
XL - eXtra Large
XLF - eXtensible Logfile Format
XLF - XL Fortran
XLIFF - XML Localization Interchange File Format
XLL - XML Link Language
XM - eXtended Module
XMAN - eXtended Metropolitan Area Network
XMAPI - eXtended Messaging Application Program Interface
XMCL - eXtensible Media Commerce Language
XMI - eXtended Memory Interconnect
XMI - XML Metadata Interchange
XML - eXtensible Markup Language
XMLA - eXtensible Markup Language for Analysis
XMLP - eXtensible Markup Language Protocol
XMLRPC - eXtensible Markup Language Remote Procedure Call
XMLSS - eXtensible Markup Language SpreadSheet
XMM - eXtended Memory Manager
XMOS - Cross Media Optimization Study
XMP - eXtended Management Pack
XMP - eXtensible Metadata Platform
XMP - X/open Management Protocol
XMPP - eXtensible Messaging and Presence Protocol
XMS - eXtended Memory Specification
XMS - eXtended Multiprocessor operating System
XN - eXecution Node
XNFS - X/Open Network File System
XNI - Xerces Native Interface
XNM - eXpansion Node Manager
XNS - Xerox® Network Services
XNS - Xerox® Network Standard
XNS - Xerox® Network Systems
XNSCP - Xerox® Network Services Control Protocol