| mac | PATCHMASTER Macro File |
| macbin | Macbinary Encoded |
| macro | Tecplot 360 Macro Data |
| mad | Microsoft Access Module Shortcut |
| mads | Metadata Authority Description Schema Data |
| mai | Microsoft Mail |
| mail | NeoPlanet Mail Data |
| mailstationery | Apple Mail Stationery Data |
| mailtoloc | Mac OS X Finder Mail Internet Location |
| main | FileMaker Pro Dictionary Data |
| maj | CAMduct Job Data |
| maker | Adobe FrameMaker Data |
| mamc | Auto Mouse Click Script |
| maml | Microsoft Assistance Markup Language Data |
| mamp | MAMP Related Data |
| man | AquaCrop Field Management Data |
| map | WAsP Terrain Map |
| map | TECkit Mapping Table |
| map | Map Data |
| maplet | Maple Maplet File |
| maplib | Mscape Map Data |
| mapx | MapDotNet UX Map File |
| marker | Microsoft Windows 10 System Data |
| marshal | Marshal Data Migration Model |
| mash | Java Mashing Data |
| mask | Adobe SpeedGrade Color Mask |
| mat | Altair FEKO Matrix Element Data |
| mat | Kerkythea Material Data |
| material | Rigs of Rods Texture Reference |
| math | AnalyticMath Data |
