Electro Designs

.X    LEX Program File
        Amapi 3D Modeling (prior to version 4)
        AVS Image   
  .X01  Paradox Secondary Index (can be 01 to 09)
  .X16  Macromedia Program Extension (16-bit)
  .X32  Macromedia Program Extension (32-bit)
  .X3D  Xara 3D Project File
  .X4M  TeamLinks Mail File Data
  .X5   Rockwell Software Logix 5 File
  .XA   Extended Architecture File
        The Sims (Maxis) Extensive Audio
        File on PSX Disc
  .XAB  Xenis Mail Address Book
  .XAR  Corel Xara Drawing
  .XBM  X Bitmap Graphic  [Viewer]  
  .XCF  GIMP Image File  [GIMP]
  .XFD  Adobe Text File (unconfirmed)
  .XFN  Ventura Printer Font
  .XFT  Chiwriter 24 Pin Printer Font
  .XFX  Fax File (various)
  .XGR  MS Graph Edit XML Graph
  .XI   Fast Tracker 2 Instrument
        ScreamTracker Instrument File
  .XIF  Wang Image File
        Xerox Image File
  .XIP  Hotbar Image Compression Format
  .XLA  Excel Add-in
        Xlib Archive
  .XLB  Excel File
  .XLC  Excel Chart
  .XLD  Excel Dialog
  .XLG  Xnetech Engraving Logo File
  .XLK  Excel Backup
  .XLL  Excel Add-in (Dynamic Link Library)
  .XLM  Excel Macro
  .XLR  MS Works File
  .XLS  Excel Worksheet
        DATAIR Data Import Specification Translation File
  .XLT  Excel Template
        Procomm Plus Translation Table
        Lotus Translation Table
  .XLV  Excel VBA
  .XLW  Excel Workspace
  .XM   Sound File
        Fast Tracker 2 Extended Module
  .XMB  X-Wing Mission Briefing File
  .XMI  Winamp Extended Midi File
  .XML  Extensible Markup Language File  [XML]
  .XNF  Standard Network File Form
  .XNG  OM2 911 Xchange Version 6 Document
  .XNK  Exchange Shortcut
  .XOT  Xnetech Job Output File
  .XPL  Music File
  .XPM  X Picsmap Graphic  [Viewer]
  .XQT  SuperCalc Macro Sheet
        Waffle Executable File
  .XRF  Cross Reference
  .XR1  Epic MegaGames Xargon File
  .XRF  Crossreference File
  .XS   Hummingbird Exceed File
  .XSL  XML Stylesheet  [XML]
  .XSM  LEXIS-NEXIS Tracker
  .XT*  Crosstalk Related File
  .XTB  LocoScript External Translation Table
  .XTR  RealArcade Compressed Data File
  .XUL  XML User Interface Language
  .XVU  BOClean Database File
  .XWD  X Windows Dump  
        Crossdown Puzzle File
  .XWF  Yamaha XG Works File
  .XWI  X-Wing Mission File
  .XWK  Crosstalk Keyboard Mapping
  .XWP  Crosstalk Session
        Xerox Writer Text File
  .XX   Xxencoded File
  .XXE  Xxencoded File
  .XXX  Singer Sewing Machine Professional SewWare File
  .XY   XYWrite Text File
  .XY3  XYWrite Text File
  .XY4  XYWrite IV Document
  .XYP  XYWrite III Plus Document
  .XYW  XYWrite Windows 4.0 Document