| mpx | Alpha Five Temporary Index |
| mpx | Visual FoxPro Compiled Menu Program |
| mq4 | MetaQuotes Language 4 Source Code |
| mq5 | MetaQuotes Language 5 Source Code |
| mqh | MetaTrader MetaQuotes Language 4 Header |
| mql | MetaTrader MetaQuotes Language 4 File |
| mql4 | MetaTrader MetaQuotes Language 4 File |
| mql5 | MetaTrader MetaQuotes Language 5 File |
| mqt | MetaTrader MetaQuotes Language 4 Template |
| msb | Oracle Binary Message File |
| msct | MOPEKS Script File |
| msh | Microsoft Shell Script |
| msh | MaxL Shell Script |
| msh1 | Microsoft Shell Script |
| msh2 | Microsoft Shell Script |
| msha | Microsoft Help Asset.File |
| mshc | Microsoft Help Container. |
| mshi | Microsoft Help Index.File |
| mshxml | Microsoft Shell Types File |
| msl | ProWorx NXT MSL Loadable |
| mspx | Microsoft Presentation Framework Page |
| mthd | MOPEKS Method File |
| mtn | Monotone Database |
| mtpf | Moony-TexturePacker Texture |
| mtra | MascotCapsule Resource Data |
| mtrl | Esenthel Engine Material Data |
| mtxt | MOPEKS Text File |
| mu | MuPAD Source Code |
| muf | Alpha Five Concurrent Users Data |
| mui | Multilingual User Interface Data |
| mv | Miva Script Source Code |
| mvc | Compiled Miva Script Program |
| mvq | mvQuery Query |
| mvt | Miva Merchant Module |
| mvx | Multimedia Fusion Movement Extension |
