| xmdf | eXtensible Model Data Format Data |
| xmdl | XMDL Model |
| xmdx | ExamSoft SofTest Answer Data |
| xme | GME Metamodel |
| xmef | TextMap Evidence Format Data |
| xmf | IMVU 3D Model |
| xmfa | Mauve eXtended Multi-FastA Data |
| xmfd | FileMaker Pro XML Field Data |
| xmi | XMVB Input File |
| xmit | IBM XMIT Data |
| xml-log | WinSCP XML Log |
| xmldsig | XML Digital Signature |
| xmlff | ControlSplit XML Flat File |
| xmlper | LeCroy Binary Waveform |
| xmlr | SiteScan XML Results |
| xmlt | HydPy XML Template |
| 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 |
| xmmmp | MindManager Map Part |
| xmo | XMVB Output File |
| xmod | Monarch Pro Model |
| xmp | Darktable Sidecar Data |
| xmpp | Extensible Messaging and Presence Protocol Data |
| xmps | FICO Xpress Optimizer Matrix Data |
| xmpses | Adobe Premiere Elements Chapter Point Information |
| xmpskin | XMPlay Skin Data |
| xmptf | TextMap Portable Transcript Data |