| mem | Corel WordPerfect Macro Editor Macro |
| men | MenuPro Menu Document |
| mer | Data Interchange Format |
| met | OmniPage Document |
| metastock | MetaStock Document |
| mez | MusicEase Document |
| mf1 | I-DEAS Model |
| mf2 | I-DEAS Model |
| mfp | Macromedia Flash Paper |
| mga | Manga Document |
| mge | MacGAMUT Mini Demo Data |
| mgmf | MindGenius Map |
| mgmt | MindGenius Template |
| mgmx | MindGenius XML Map |
| mgopml | MindGenius OPML Document |
| mgp | MagicPoint Presentation File |
| mgs | Equation Illustrator Vector Shapes |
| mgt | Musicnotes Guitar Guru Song |
| mgtx | MindGenius XML Template |
| mgx | Micrografx Designer Document |
| mht | Multipurpose Internet Mail Extension HTML |
| mhtl | Multipurpose Internet Mail Extension HTML |
| mhtm | Multipurpose Internet Mail Extension HTML |
| mhtml | Multipurpose Internet Mail Extension HTML |
| mhv | Husqvarna Viking MHV Embroidery |
| mhx | MakeHuman eXchange Data |
| mi | CoCreate Document |
| mic | Microsoft Image Composer File |
| mif | Adobe FrameMaker Interchange Format |
| mind | MindMeister Mindmap Document |
| mjb | MuJoCo Binary Model |
| mjbooktemplate | MacJournal Book Template |
| mjcf | MuJoCo XML Model |
| mjdoc | MacJournal Document |
| mkd | CAD6 Drawing |