| mep | Inor MePro Data |
| meps | MEPS Data |
| meq | Corel WordPerfect Macro Editor Print Queue |
| mes | SpectraMagic NX Data |
| mes | TrimeTool MES Output |
| mesa | MESA Model |
| mesh | Rigs of Rods Mesh Data |
| mesh | Microsoft DirectX D3D Mesh Data |
| mesh | Geomview Rectangularly-connected Mesh Data |
| mess | Salome-Meca Exported Message Data |
| message | WebSTAR Directory Indexer Message |
| meta | Apache META File |
| meta4 | Metalink Data |
| metadata | Acronis True Image Metadata |
| metadix | Apertium Metadix Dictionary Data |
| metalink | Metalink Data |
| metriclog | Apple iOS Diagnostic Data |
| mets | METS Data |
| mev | TIGR MultiExperiment Viewer Format Data |
| mew | MultiEdit Encoded Status Data |
| mex | Macro Express Macro File |
| mex | MAXQDA Exchange Data |
| mexp | MetaMorph NX Experiment Data |
| mf4 | ASAM Measurement Data Format File |
| mfalist | Ashampoo Photo Commander Slideshow List |
| mfasl | Mozilla Fastload File |
| mfc | CMUSphinx Features Data |
| mfcc | HTK Mel-Frequency Cepstral Coefficient Data |
| mfd | Multiframe Design |
| mfe | MobileFrame Enterprise Data |
| mff | EGI Metafile Format Data |
| mfg | PTC Creo Manufacturing Process Data |
| mfil | World of Warcraft Software Update |
| mfj | MOBCAL Input Data |
| mfl | ModFit LT Analysis Report |