| Abbreviation | Definition |
|---|---|
| XNV | nVision Report Layout |
| XOF | RenderMorphics |
| XOI | OpenIndex directory stub |
| XOM | OmniMark Source Code file |
| XOS | Xaos Tools image file Bitmap graphics |
| XOT | Xnetech Job Output File |
| XPA | SoniqSync Extended Playlist |
| XPM | X11 pixmap file Bitmap graphics (8-bit text) |
| XQL | XML Query Language file |
| XQT | SuperCalc Macro sheet |
| XQT | Waffle Executable file |
| XR1 | MegaGames Xargon Game data |
| XREF | Cross reference file |
| XRF | Cross Reference File |
| XSC | XML schema |
| XSD | XML Schema Definition |
| XSI | Xml Schema Instance |
| XSL | Xml Stylesheet Language |
| XSM | LEXIS- NEXIS Tracker |
| XSN | xyALGEBRA File |