| mlz | MLZ Data |
| mm | FreeMind MindMap |
| mm | Matrix Market File |
| mm3 | Mortgage Minder v3 Data File |
| mm3d | Misfit Model 3D Model |
| mm6 | Money Manager 6 Data |
| mmads | MMADS Chemical Modeller Input Data |
| mmap | MindManager Map File |
| mmas | MindManager Theme |
| mmat | MindManager Map Template |
| mmb | Mobile Master Backup |
| mmc | Microsoft ClipArt Gallery Catalog |
| mmcif | mmCIF Data |
| mmcollection | Mail Manager Collection Data |
| mmd | mAirList Metadata |
| mmd | Media Processing Server Audio Data |
| mmd0 | Foobar2000 Data |
| mmdb | MaxMind GeoIP2 Database |
| mmdb | Molecular Modeling Database |
| mmdl | Sapphire Structure Model Data |
| mme | MIME Encoded Data |
| mmf | Microsoft Mail Message Format Data |
| mmi | Media Processing Server Index File |
| mmjb | Musicmatch Jukebox Data |
| mmjb_mime | Musicmatch Jukebox MIME Data |
| mmjs | Adobe Dreamweaver Javascript |
| mml | Media Catalog MML File |
| mmmp | MindManager Map Part |
| mmms | MindManager Map Marker List |
| mmn | Memory-Map Navigator Data |
| mmo | Memory-Map Overlay File |
| mmod | MacroModel Molecular Mechanics Data |
| mmr | Inertial Explorer Mounting Data |
| mmr | Sybase PowerDesigner Multimodel Report |
| mmt | Nimbus 7 SAMS MMRVT Data |