| mm | Metamath ASCII Database |
| mm | NeXtMidas Macro |
| mm3 | MM3 Chemical Modeller Data |
| mm3 | Mortgage Minder v3 Data File |
| mm3d | Misfit Model 3D Model |
| mm5 | Makromat Macroeconomic Model Data |
| mm6 | Money Manager 6 Data |
| mmads | MMADS Chemical Modeller Input Data |
| mman | Emailer MMAN Data |
| mmap | MindManager Map File |
| mmas | MindManager Theme |
| mmat | MindManager Map Template |
| mmb | Mobile Master Backup |
| mmb | Money Manager EX Data |
| mmb | Tecplot Data |
| mmc | MicroCase Boundary Data |
| mmc | Microsoft ClipArt Gallery Catalog |
| mmcif | mmCIF Data |
| mmcollection | Mail Manager Collection Data |
| mmd | Cumulate Draw MMD Data |
| mmd | MacroModel Chemical Modeller Output |
| mmd | MacroModel Molecular Mechanics Data |
| mmd | mAirList Metadata |
| mmd | Mangodata Database |
| mmd | Media Processing Server Audio Data |
| mmd | Summit Membership Manager Database |
| mmd0 | Foobar2000 Data |
| mmdb | MaxMind GeoIP2 Database |
| mmdb | Molecular Modeling Database |
| mmdl | Sapphire Structure Model Data |
| mmdr | Adobe Director MMDR Data |
| mme | MIME Encoded Data |
| mmes | Mastersizer 3000 Data |
| mmf | Meal-Master Recipe File |
| mmf | Microsoft Mail Message Format Data |
