| mtml | Meaningful Text Markup Language Data |
| mtn | PTC Creo Tool Motion Parameter Data |
| mto | FastCAM MTO Data |
| mtp | SpectraMagic NX Template |
| mtst | MotionTracking RAW Image Stack Data |
| mtt | FastCAM MTO Data Template |
| mtt | MetadataTouch Template |
| mttfs | MadgeTech 4 Report Data |
| mtu | Match! User Database |
| mtw | Minitab Worksheet |
| mtw | SDL Trados MultiTerm Termbase Data |
| mtx | GROMACS Molecular Dynamics Hessian Matrix Format Data |
| mu | Quattro Pro for DOS Menu Data |
| mub | ExtractNow Data |
| muc | Music Collector Collection Data |
| mucow | Adobe Muse Configurable Options Widget |
| mud | Textease Database CT Multi-user Database |
| mudp | Active Safety System Internal Log |
| mulib | Adobe Muse Widget Library |
| mult | SAM Multiple Domain Alignment Output |
| mum | MATLAB Unit Operation Model |
| muphlp | MuPAD Help Data |
| murl | Maxthon Browser URL Data |
| musc | eXtendable Wad Editor MUSC Data |
| musx | Min-U-Script Xpress Data File |
| mut | Integrative Genomics Viewer Mutations List |
| mv85 | Adobe Director for Mac Video |
| mv93 | Adobe Director for Mac Video |
| mv95 | Adobe Director for Mac Video |
| mvd | MACE Velocity Data |
