| mgz | Compressed MGH MRI Data |
| mhd | ITK MetaImage Header |
| mhe | Hackshield Heuristic Engine File |
| mhg | MHEG-5 Multimedia Data |
| mhl | Media Hash List |
| mhm | Microsoft Mouse and Keyboard Center Macro |
| mhp | Maths Helper Plus Data |
| mhs | Xilinx Microprocessor Hardware Specification |
| mi2 | AutoDesk Softimage Data |
| miaf | InstallAware Setup Dialog Rules |
| mib | SNMP MIB File |
| midata | Mine-imator Data |
| mif | Elmer Mesh Generator Input File |
| mif | Xilinx CORE Generator Memory Initialization File |
| mif | mAirList Inline File |
| miframes | Mine-imator Keyframes Data |
| migtable | Microsoft Windows Migration Table Data |
| miigx | SaveGame Manager GX Mii Data |
| mil | PTC Creo Milling Parameter Data |
| milanguage | Mine-imator Language Data |
| millpst | BobCAD-CAM Post Processor Data |
| mim | MIME Encoded Data |
| mime | MIME Encoded Data |
| mimodel | Mine-imator Model Data |
| mindnode | MindNode Document |
| mini | Mini V Presets Data |
| minibank | Mini V Presets Data |
| miniml | MINiML File |
| miobject | Mine-imator Object Data |
| miparticles | Mine-imator Particles Data |
| mir | Mail.dat Manifest Individual File |
| mit | MineEdit Inventory Template |
| miv | MapImagery Vendor Profile |
| mix | VentaFax Voice Message Batch |
| mixn | Apple Guide Addition Data |