| main | FileMaker Pro Dictionary Data |
| mamp | MAMP Related Data |
| map | WAsP Terrain Map |
| map | Map Data |
| map | TECkit Mapping Table |
| maplet | Maple Maplet File |
| mapx | MapDotNet UX Map File |
| marshal | Marshal Data Migration Model |
| mask | Adobe SpeedGrade Color Mask |
| material | Rigs of Rods Texture Reference |
| math | AnalyticMath Data |
| mauve | Mauve Alignment Data |
| maxc | Autodesk 3D Studio MAX Container |
| maxd | PaperPort Annotation Data |
| maxfr | MaxView Web Pointer Data |
| mb1 | Math Blaster 1 Data |
| mb1 | UltraEdit Menus Data |
| mbak | Quantrix Modeler Backup Data |
| mbb | CARAIBES Bathymetric Data |
| mbdb | iTunes Backup Manifest Database |
| mbdx | iTunes Backup Manifest Database |
| mbg | CARAIBES Georeferenced Depth Data |
| mbg | Microsoft Mail Mailbag |
| mbk | dBASE IV Multiple Index Backup |
| mbl | Vernier Logger Pro Data |
| mbn | Sony-Ericsson Phone Main Firmware |
| mbox | Unix Mailbox |
| mbp | Mobipocket Reader Data |
| mbp | Modbus Poll Data File |
| mbs | Opera Mail Mailbox |
