| X | AVS image (SDSC Image Tool) |
| X | Source code file (Lex) |
| XA0 | Dos help file (Xtree) |
| XAR | Corel Xara drawing |
| XBM | A MIME 'X11" bitmap image |
| XB0 | Dos help file (Xtree) |
| XC0 | Dos help file (Xtree) |
| XDL | XML Schema file |
| XD0 | Dos help file (Xtree) |
| XDR | XML data reduced file |
| XE0 | Dos help file |
| XFN | Printer font file (Xerox) |
| XFN | Printer font file (Ventura Publisher) |
| XFT | Printer font file (24 Pin) (ChiWriter) |
| XFX | Fax Document (Various) |
| XHTML | eXtensible hypertext markup language |
| XI | Instrument sample file (ScreamTracker) |
| XI | Instrument file (FastTracker II) |
| XIF | Wang imaging file (Included with Windows 95) |
| XIF | Image file (Xerox) (same as TIF) |
| XIF | Image file (Pagis) |
| XIF | Image file eXtended (ScanSoft) the file is similar to TIFF and is a (Pagis) native format |
| XLA | Add-in file (Microsoft Excel) |
| XLA | Archive (Xlib) |
| XLB | Toolbar file (Microsoft Excel) |
| XLB | Datafile (Microsoft Excel) |
| XLC | Chart file (Microsoft Excel) |
| XLD | Dialogue file (Microsoft Excel) |
| XLK | Backup file (Microsoft Excel) |
| XLL | Add-in file (Microsoft Excel) |
| XLL | Dynamic link library (Microsoft Excel) |
| XLM | Macro file (Microsoft Excel) |
| XLS | Worksheet file (Microsoft Excel) |
| XLT | Template file (Microsoft Excel) |
| XLT | Translation table (Lotus 1-2-3) |
| XLT | Translation table (Symphony) |
| XLT | Translation table (Procomm Plus) |
| XLV | VBA module (Microsoft Excel) |
| XLW | Workbook (Microsoft Excel) |
| XM | Music module (MOD) (Fast Tracker 2) |
| XMI | Compressed midi music (eXtended) |
| XML | eXtensible markup language |
| XML | General XML instance document |
| XNF | Network file (Standard) |
| XNK | Shortcut file (Microsoft Exchange) |
| XOF | Image file (Render Morphics) |
| XON | Datafile (Axon) |
| XPM | X BitMap format |
| XQT | Executable file (Waffle) |
| XQT | Macro file (SuperCalc) |
| XXX | XXXX |
| XR1 | Data file (Epic Megagames Xargon) |
| XRF | Cross-reference file (Generic) |
| XSD | XML schema description file |
| XTB | External translation table (LocoScript) |
| XTP | Data file (Xtree) |
| XWD | X Window Dump format (SDSC Image Tool) |
| XWF | Works file (Yamaha XG) (MIDI sequencing) |
| XWK | Keyboard mapping file (Crosstalk) |
| XWP | Session file (Crosstalk) |
| XWP | Text file (Xerox Writer) |
| XX | Compressed ASCII archive (XXENCODE) |
| XXE | Compressed ASCII archive (XXENCODE) |
| XY | Text file (XYWrite) |
| XY3 | Document file (XYWrite III) |
| XY4 | Document file (XYWrite IV) |
| XYP | Document file (XYWrite III Plus) |
| XYW | Document file (XYWrite for Windows 4.x) |
| X01 | Secondary index file (Paradox) |
| X02 | Secondary index file (Paradox) |
| X03 | Secondary index file (Paradox) |
| X04 | Secondary index file (Paradox) |
| X05 | Secondary index file (Paradox) |
| X06 | Secondary index file (Paradox) |
| X07 | Secondary index file (Paradox) |
| X08 | Secondary index file (Paradox) |
| X09 | Secondary index file (Paradox) |
| X10 | Dos help file (Xtree) |
| X16 | Macromedia Extra (program extension), 16 bit |
| X20 | Dos help file (Xtree) |
| X30 | Dos help file (Xtree) |
| X32 | Macromedia Extra (program extension), 32 bit |
| X40 | Dos help file (Xtree) |
| X50 | Dos help file (Xtree) |
| X60 | Dos help file (Xtree) |
| X70 | Dos help file (Xtree) |
| X80 | Dos help file (Xtree) |
| X90 | Dos help file (Xtree) |
2010 Liberty Boy
Le Havre