| xmdx | ExamSoft SofTest Answer Data |
| xme | GME Metamodel |
| xmef | TextMap Evidence Format Data |
| xmf | IMVU 3D Model |
| xmfa | Mauve eXtended Multi-FastA Data |
| xmi | XMVB Input File |
| xmldsig | XML Digital Signature |
| xmlper | LeCroy Binary Waveform |
| xmlr | SiteScan XML Results |
| xmlz | ZennoPoster MP Template Data |
| xmm | Autodesk 3D Studio MAX XML Animation Map |
| xmmap | MindManager XML Map |
| xmmas | MindManager XML Theme Data |
| xmmat | MindManager XML Template |
| xmo | XMVB Output File |
| xmod | Monarch Pro Model |
| xmp | Darktable Sidecar Data |
| xmps | FICO Xpress Optimizer Matrix Data |
| xmpses | Adobe Premiere Elements Chapter Point Information |
| xmpskin | XMPlay Skin Data |
| xmptf | TextMap Portable Transcript Data |
| xmp_bin | Parasolid CAD Binary Partition Data |
| xmp_txt | Parasolid CAD ASCII Partition Data |
| xmt_bin | Parasolid CAD Binary Parts Data |
| xmt_txt | Parasolid CAD ASCII Parts Data |
| xmu | eXtendable Wad Editor Data |
| xmx | Autodesk AutoCAD External Message File |
| xmzx | ExamSoft SofTest Exam Data |
| xnf | Extensible Numerical File Format Data |
| xng | FishXing Data |
