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XIF -
XKS - IBM Softcopy Reader PDF Extended Bookshelf File
XBK - SMART Board Slide Collection
XHD - HappyFish XML Data File
XAS - Playstation Video
XCDATAMODEL - Xcode Core Data-based Data Model
XDO - OutDo Outline File
XEV - eManager XML Autoupdate Definition
XLSENX - egis Encrypted Excel XLS File
XLSXENX - egis Encrypted Excel Open XML XLSX File
XPX - XML Format File
XPX - RAFTS-XP Macro File
XPX - Dungeons & Dragons Core Rules 2 with Expansion
XCD - WarpIN CID (Configuration, Installation, Distribution) File
XCT - XVI32 Conversion File
X3DB - X3D Binary Format File
X3DBZ - X3D GZipped Binary Format File
X3DV - X3D Classic VRML File
X3DVZ - X3D GZipped Classic VRML File
X83 - GAEB DA2000 XML and XML File
XAML - Windows Presentation Foundation Object Model XML-based Markup Language
XBIN - RegSupreme License File
XDD - XFIT XDD Format Data File
XEB - Apabi eBook
XFB - LonMark Binary Device Interface File Format
XFO - LonMark Optimized Device Interface File
XMCD - Xmcd CD Information
XSP - Cross Stitch Professional Design File
XSPF - XML Shareable Playlist Format
XTEL - Xtelplot File Format
XVC - Verge Compiled Game Code
XYZI - 3rdTech Scanner File
XYZRGB - 3rdTech Scanner File
XIF - eXtended Image File Format
XIF - Often a Fax Image (TIFF) File
XIF - Wang Image File
XIF - Xerox Image File
X - Alysis SuperDisk Self-extracting Archive
X - Amapi 3D Modeling
X - LEX Program File
X - Stardent AVS X Image
X - Xview Object
X - XBLite Program File
X01 - Paradox Secondary Index
X02 - Paradox Secondary Index
X03 - Paradox Secondary Index
X04 - Paradox Secondary Index
X05 - Paradox Secondary Index
X06 - Paradox Secondary Index
X07 - Paradox Secondary Index
X08 - Paradox Secondary Index
X09 - Paradox Secondary Index
X10 - X Window Dump Bitmap
X11 - X Windows System Window Dump Bitmap
X13 - Hooligans
X16 - Macromedia Program Extension
X3D - x3D and xdart Formats
X4M - TeamLinks Mail File Data
X5 - Rockwell Software Logix 5 File
X64 - C64 Emulator Disk Image
XA - Extended Architecture File
XA - File on PSX Disc
XA - Gear CD Suite File
XAB - Xenis Mail Address Book
XAD - eXotic AdLib Format
XAN - XANIA Browser
XAN - xyALGEBRA File
XAR - Corel Xara Drawing
XBE - Xbox Executable
XBF - Database File
XBF - Emperor Battle for Dune
XBL - Extensible Binding Language
XBL - XBLite Program File
XBM - X Bitmap Graphic
XBS - ETAK MapBase
XBW - Crossword
XB~ - IC File
XC - X Server Constant Screen Image Bitmap
XCK - Extended Crack File
XCL - Xtree for Win Script
XCR - Warlords Battlecry
XD - CCS-lib.2 Examples Motif-CC File
XDE - Tgif-3.0 File
XDF - Extended Disk Format Image
XDF - Milnta APL Transfer Function
XDF - Workshare Synergy File
XDF - X68000 Image File
XDP - UNIX File
XDS - OpenGL Performer Script
XDS - XDS X-ray Detector Software
XDW - Milnta APL Transfer Function
XEX - KERMIT Control File
XEX - Renamed .EXE File
XFD - XML Form in XFDL Format
XFDL - XML Form in XFDL Format
XFI - LaTex Figures File
XFM - OmniForm XML Format
XFN - Ventura Printer Font
XFR - Symantec Norton Anti-Virus Corporate Version Failed Update
XFR - Ventura Publisher Bitmap Editor Font File
XFS - eRacer Sound File
XFT - ChiWriter 24 Pin Printer Font
XFX - Fax File
XG0 - Database Index; Paradox Secondary Index
XG1 - Database Index; Also XG2, XG3...
XG1 - Techno Toys XG-909 MIDI Drum Machine File
XG2 - Database Index; Also XG3, XG4…
XG3 - Database Index; Also XG4, XG5…
XG4 - Database Index; Also XG5, XG6…
XG5 - Database Index; Also XG6, XG7…
XG9 - Techno Toys XG-909 MIDI Drum Machine File
XGL - MegaBitz Graphics Language File
XGM - Techno Toys XG-909 MIDI Drum Machine File
XGO - LogMate for Windows File
XGO - Paradox Database-related File
XGZ - MegaBitz Vector Drawing
XHDML - XML Version of HDML File
XHT - Extensible HyperText Markup Language File
XHTM - Extensible HyperText Markup Language File
XHTML - Extensible HyperText Markup Language File
XHTML - Libxml HTML File
XI - Fast Tracker 2 Instrument
XI - ScreamTracker Instrument File
XIM - X11 Xim Toolkit Bitmap
XIP - Hotbar Image Compression Format
XIP - HP95 Execute-in-place Program
XJS - WinExplorer Java Script
XJT - Compressed GIMP Image with Properties of GIMP
XJTGZ - Compressed GIMP Image with Properties of GIMP
XJTZ2 - Compressed GIMP Image with Properties of GIMP
XL - Old Amiga Movie Format
XL - XBLite Program File
XL$ - Modem Bitware Fax Disk2 File
XLA - Xlib Archive
XLE - Cooktop File
XLF - XLIFF Document
XLG - Xnetech Engraving Logo File
XLT - Procomm Plus Translation Table
XLX - XoloX Incomplete Download File
XM - Fast Tracker 2 Extended Module
XM - Sound File
XMAP - File That Controls How XML/XSL Gets Served
XMB - X-Wing Mission Briefing File
XMF - Milnta APL Transfer Function
XMI - EverQuest File
XMI - Winamp Extended MIDI File
XMI - XML Metadata Interchange Format
XML - Extensible Markup Language File
XMP - Graphic File
XMP - Spice Pspice Library File
XMS - ViewCafT XML Markup Session
XMS - XMS-Tracker
XMT_TXT - Parasolid CAD File
XMV - Milnta APL Transfer Function
XMX - Character Set File
XMZ - Fasttracker 2/Extended Module
XMZ - MegaView XGL Movie
XNF - Standard Network File Form
XNG - OM2 911 Xchange Version 6 Document
XNT - Spice Pspice Library File
XOF - RenderMorphics
XOI - eZediaMX and eZedia Player Locked Presentation Document
XOS - Xaos Tools Bitmap Image
XOT - Xnetech Job Output File
XP - System Utility File
XPIX - Nonogram Puzzle
XPK - Spice Pspice Library File
XPL - Music File
XPL - WinExplorer Simple Script
XPL - Xset Plug-ins File
XPM - BMC Software Patrol UNIX Icon File
XPM - X Pixmap Graphic
XPO - Omega Research ProSuite
XPO - X-port Version 1
XPP - xCOMPOSER.pro Multimedia Data File
XPS - X-port Version 2
XPT - XPCOM Type Library
XPW - Leading Market Technologies EXPO
XPY - MarketBrowser
XQT - SuperCalc Macro Sheet
XQT - Waffle Executable File
XR1 - Epic MegaGames Xargon File
XRC - wxWindows/wxPython Resource File
XREF - AIX Cross Reference File
XRF - Cross Reference
XRF - Crossreference File
XRL - XML Résumé Library Résumé
XRL - OSCAR Rules File
XRW - Architag XRay XML Editor
XS - Hummingbird Exceed File
XS8 - SIMUL8
XSB - Sokoban++ Level File
XSC - XML Schema
XSD - XML Schema
XSF - Milnta APL Transfer Function
XSL - FileMaker Database Design Report Template
XSL - Steuer2001 File
XSL - XML Stylesheet
XSLT - XSL Transform File
XSM - LEXIS-NEXIS Tracker
XSN - xyALGEBRA File
XSTEP - XStep DWI Maker File
XSU - Fortran Libf77 File
XSUM - Clapack File
XSW - Milnta APL Transfer Function
XT - FastTracker Music Track
XT* - Crosstalk Related File
XTD - XML Type Definition
XTP - XTree Data File
XTP - XTreeGold Overlay
XTR - RealArcade Compressed Data File
XTS - Babya Desktop Shell System Software Extension
XTS - CSPro File
XUF - Milnta APL Transfer Function
XUW - Milnta APL Transfer Function
XV - Khoros Visualization Image File
XVB - WinExplorer VB Script
XVG - GROMACS Output File
XVID - XviD CODEC
XVP - Xview Package File
XVS - Xview Scene Package File
XVU - BOClean Database File
XWC - Crosstalk for Windows Compiled Script
XWD - Crossdown Puzzle File
XWD - X Windows Dump
XWF - Yamaha XG Works File
XWI - X-Wing Mission File
XWK - Crosstalk Keyboard Mapping
XWP - Crosstalk for Windows Phone book
XWP - Crosstalk Session
XWP - Xerox Writer Text File
XWS - Crosstalk for Windows Script
XWZ - Xset Wizards File
XWZ_1 - Xteq X-Setup File
XX - Arcedit Temporary File
XX - Xxencoded File
XXE - Xxencoded File
XXI - GameSpy Arcade
XXL - Archive
XXT - Extension DLL
XXX - Compucon/Singer PSW Embroidery Design File
XXX - Controlware VJ400 Digital CCTV Recording
XXY - SPARC Executable Script File
XY - XYWrite Text File
XY3 - XYWrite Text File
XY4 - XYWrite IV Document
XY4V - XYWrite IV document
XYP - XYWrite III Plus Document
XYW - XYWrite Windows 4.0 Document
XYZ - XMol XYZ
XYZ - Graph Coordinates
XYZ - XYZZLY Plug-In for RealPlayer
X_B - Parasolid CAD File
X_T - Parasolid CAD File
XMF - eXtensible Data Model and Format
XPS - XML Paper Specification

4pi Analysis, Inc.

XRT - Revolution EDX Spectrum Export File in Xraytor Format

Ability Software

XSS - Ability Office Spreadsheet

Accelrys Software Inc.

XDR_TOR - Insight II Binary Torsion File
XHESSIAN - Insight II Hessian File

Acucorp, Inc.

XFD - Acu4GL Extended File Description

Adobe

XFDF - Acrobat Forms Document
XFM - Audition Transform Effect
XFT - LiveCycle Designer Form
XMP - Adobe Extensible Metadata Platform

Altair Communications Corporation

XTML - XML4web Virtual HTML File

Applied Information Systems, Inc.

XS3 - XESS Worksheet
XS4 - XESS Worksheet
XS5 - XESS Worksheet

Atari

XFD - Atari Disk Image

Autodesk, Inc.

XLG - AutoCAD XREF Log
XLO - Inventor Export Journal
XMS - AutoCAD External Message
XMX - AutoCAD External Message Compiled File

Avid Technology, Inc.

XSI - Softimage XSI 3D Model

Bettinger Software

XYZ - Förderdiagnose Data File

Brixx Solutions Ltd.

XXA - Brixx Planner Account Detail Chart
XXD - Brixx Planner Calendar File
XXG - Brixx Planner Graph
XXP - Brixx Planner Plan File
XXR - Brixx Planner Report File

Chaos systems AB

XR - Chaos Desktop External Reference File

Christian Maas

XSC - XVI32 Script File

Codec Games

XDT - Xscript Data Packet
XPK - Xscript Package
XRG - Xscript Game Registry
XSC - Xscript Script

Corel Corporation

XXX - Paint Shop Photo Album Panorama

Creature House Ltd.

XPR - Expression 3 Graphic File

D-Link Systems, Inc.

XDSL - D-Link Router UK Firmware Update File

Dan Suciu, AT&T Labs-Research and Hartmut Liefke, University of Pennsylvania

XMI - XMill Compressed XML

Data Becker

XPK - XPK Player Compressed Audio

DATAIR Employee Benefit Systems, Inc.

XLA - Data Import aka Dimport Translation Table

Datel Design and Development Ltd.

XPC - ActionReplay Saved Code

DecisionSoft Limited

XST - X-Tract XML Script

Decisive Tools (USA) Pty Ltd

XPJ - X-Pert for Windows File

Delorme

XMH - XMap Handheld Street Atlas USA Map and Route File
XMP - XMap Project Data

DP Software

XSS - Cross Stitch Professional Design File

Electronic Arts (Maxis)

XA - The Sims Extensive Audio

Energy Scitech Ltd.

XMLBACKUP - EnABLE Backup File

Enterbrain, Inc.

XYZ - RPG Maker Graphic Format

Experior Corporation

XRP - Experior Practice Management Report

Fuji Xerox Co., Ltd.

XDW - DocuWorks File

Fulford Software Solutions

XST - Easy Cross Cross Stitch Design

Funcom

XARC - The Longest Journey Sound File

GeoConcept SA

XGO - GeoConcept Add-On

Giunti Interactive Labs S.r.l. (a company of Giunti Publising Group)

XPT - eXact Packager Models

greenworks organic-software

XFR - Xfrog Vegetation File

Haliplex Communication Systems

XC2 - HPXView DACCS Configuration
XCN - HPXView DACCS Configuration

IBM

XLT - Lotus Translation Table

IHMC

XCM - CmapTools Exported Concept Map
XTM - CmapTools Exported Topic Map

InstallShield Software Corporation

XPO - Expo Product Tours Project

Intercon Associates Inc.

XPW - Accessible FormNet Fillable Form

Jan Hubicka, Thomas Marsh, Zoltan Kovacs and Others

XPF - XaoS Position File

Jan T. Sott

XPY - xpy Settings File

John Galt Media, Inc.

XDB - HyperCD HyperLOCK

LocoScript Software

XTB - LocoScript External Translation Table

LonMark International

XIF - LonMark Device Interface File

Macromedia

X32 - Macromedia Program Extension

MDL Information Systems, Inc.

XYZ - MDL Molfile Co-ordinate Animation Format

Microsoft

X - Direct3D Object
XAB - Mail Address Book
XAP - Xbox Dashboard Script
XAR - Excel AutoRecover File
XBX - XBox Image File
XDR - BizTalk XML-Data Reduced Schema
XGR - Graph Edit XML Graph
XIP - Xbox Dashboard
XIX - IIS NNTP Subject Lists
XL - Excel Spreadsheet
XLA - Excel Add-in
XLB - Excel Worksheet
XLC - Excel Chart
XLD - Excel Dialog
XLK - Excel Backup
XLL - Excel Add-in
XLM - Excel Macro
XLR - Works
XLS - Excel Worksheet
XLS - Works Spreadsheet
XLSHTML - Excel HTML Document
XLSMHTML - Excel Archived HTML Document
XLSX - Excel Microsoft Office Open XML Format Spreadsheet
XLT - Excel Template
XLTHTML - Excel HTML Template
XLV - Excel VBA
XLW - Excel Workspace
XLXML - Excel XML Worksheet
XNK - Exchange Shortcut

Microsoft Corporation

XBE - Xbox Executable
XEX - Xbox Executable
XLSX - Excel Microsoft Office Open XML Format Spreadsheet
XLR - Works Spreadsheet or Chart
XSN - InfoPath Dynamic Form/Template
XAR - Excel AutoRecover File
XDR - BizTalk XML-Data Reduced Schema

MIDI Manufacturers Association Incorporated

XMF - Extensible Music File Format

Mozilla

XPI - Mozilla/Firefox Browser Extension Archive
XUL - XML User Interface Language

NevoSoft

XNML - NML Language Language Extension

Nice Productions

XA2 - Exam Editor Question Groups

Oracle Corporation

XSQL - Oracle XSQL Servlet XSQL Template File

PicturePlayer

XGP - PicturePlayer Password Protected Files
XGS - PicturePlayer Scrambled Files

Pressit

XPR - exPresset CD Label

Quark, Inc.

XTG - QuarkXPress Tags File

Real

XRS - Realplayer Plug-in External Resources File

Republicorp Virtual Media

XDK - XML Development Kit Project

S.A.D. GmbH.

XMD - GameJack Virtual CD or DVD Image

Schneider Electric

XDF - ProWORX Nxt Extended Memory Data

Sigma

X3F - Sigma Camera RAW Picture File

Softnyx

XFS - GunBound

SoniqCast, LLC

XPA - SoniqSync Extended Playlist

Sony Corporation of America

XA - Playstation Video

Stardock Corporation, Inc.

XPTHEME - Winstyles Theme

StationeryCentral.com, Inc.

XCS - BuzzLetter Encrypted Stationery Template
XCZ - BuzzLetter Zipped Collection of Encrypted Stationery Templates

Stilo

XIN - OmniMark Include File
XMD - OmniMark Source Code
XOM - OmniMark Source Code

Stream Systems Technology Center, USDA Forest Service

XNG - FishXing Culvert Data File

Sybase, Inc.

XRL - PowerDesigner Report

Symantec

XDB - Norton AntiVirus Update File
XPM - DESQview Macro

Symantec Corporation

XDS - Symantec Store Download Manager Partial Download

The GIMP Team

XCF - GIMP Image File

The House of X-Plane

XPL - X-Plane Plug-In

The Xprotector Team

XPF - X-Protector Project

Tony D. Jones

XPB - XPB! Basic Source Code

Ultrapico

XSO - Expresso Project File

VMware, Inc.

XVM - VMware Virtual Machine Console

Volantis Systems Ltd.

XDIM - Multi-Channel Server
XDRUID - XDIME Player Skin
XPTOC - XDIME Player Table of Contents

Wattle Software

XWP - XMLwriter XML Editor Project File

Web3D Consortium

X3D - X3D File

Wizards of the Coast, Inc.

XPT - Dungeons & Dragons Core Rules 2

X-Bite.co.uk

XBP - XBWML X-Bite.co.uk Markup Language

X-Genics Ltd.

XEF - eManager Form Data
XEZ - eManager Template Package

X1 Technologies, Inc.

X1 - X1 Desktop Search Saved Search File

XactCommerce

XACT - XactScript File

Xara

X3D - Xara 3D Project File
XAR - Xara X Vector Drawing
XWS - Xara Webstyle File

Xara Group Limited

XAR - Xara X Vector Drawing

XboxMediaCenter Project

XPR - XBMCTex/Xbox Media Center Graphic File

XcelleNet

XEC - Afaria

XelaSoft

XSA - XSA Raw Disk Image

Xerox

XFC - Docuprint N17 Printer Firmware

XGenics Ltd.

XEM - eManager Metering Unit Credits for File Use
XEP - eManager File Packing Definition
XES - eManager XML UI Definition for Skins
XET - eManager XML Definition of eManager Process

XMLAuthor, Inc.

XMFG - MediaForge Runtime Player Distribution Project