| ximp | XOS Digital Export Package |
| xip | Photo Mechanic Metadata File |
| xir | XML Intermediate Representation Data |
| xit | SpatialAnalyzer Data |
| xit64 | SpatialAnalyzer Data |
| xix | Microsoft IIS NNTP Subject Lists |
| xjf | OmniPage BatchManager Job |
| xjsw | Tarsia Puzzle Data |
| xkb | X Keyboard Extension Data |
| xkm | X Keyboard Compiled Keymap Data |
| xkp | X-Keys Pro Data |
| xkt | Keysight Calibration Kit Data |
| xl2 | XL2 Analyzer Data |
| xl2r | XL2 Analyzer Data |
| xla5 | Microsoft Excel 5 for Mac Add-in |
| xlamenx | Egis Encrypted Excel XLAM Document |
| xlb4 | Microsoft Excel 4 for Mac Toolbars Data |
| xlb5 | Microsoft Excel 5 for Mac Toolbars Data |
| xlb8 | Microsoft Excel 98 for Mac Toolbar Setup |
| xlbn | Microsoft Excel for Mac Toolbar Setup |
| xldb | XLerator Database |
| xle | XML Cooktop File |
| xlg | Autodesk AutoCAD XREF Log File |
| xlgc | Prosystech ExpressK Database |
| xli | 3D Studio Max IGES Input Log |
| xlkf | ABB RobotStudio License Key |
| xlm3 | Microsoft Excel 3 for Mac Macro Data |
| xln | Excellon Drill File |
| xlo | Autodesk Inventor Export Journal |
| xlo | 3D Studio Max IGES Output Log |