| mdmp | Windows Debug Dump |
| mdoc | Visual Studio Code Data |
| mdown | Markdown Document |
| mdp | Microsoft Developer Studio Project |
| mdpr | MCS Device Policy Editor Device Profile |
| mds | Microsoft DirectX Mid2stream Data |
| mdx | IBM Rational XDE Model Data |
| Multidimensional Expressions Script |
| mdyv | MCS Component Policy Editor Dynamic Visual Component |
| mea | FactoryTalk View Studio Project Backup |
| mec | Hitachi Ladder Editor Memo Comment |
| Maximus MECCA Source Code |
| med | FactoryTalk View Studio Development Application |
| mediawiki | MediaWiki Source Code |
| mel | Autodesk Maya Embedded Language Script |
| mem | Visual FoxPro MEM Data |
| Xilinx ISE User-edited Memory Data |
| meml | Minimalist Lisp Markup Language Data |
| menu | IAR System Device Selection Data |
| mep | madExcept Plugin |
| mer | FactoryTalk View Studio Runtime Application |
| mesh | Godot Engine Mesh Data |
| meshlib | Godot Engine Mesh Library |
| mex | MATLAB Executable |
| mex4 | MATLAB Sun-4/SPARC Dynamically Linked Subroutines Data |
| mexa64 | MATLAB Linux 64 Dynamically Linked Subroutines Data |
| mexds | MATLAB DECStation Dynamically Linked Subroutines Data |
| mexhp3 | MATLAB HP9000/Series 300 Dynamically Linked Subroutines Data |
| mexhp7 | MATLAB HP9000/Series 700 Dynamically Linked Subroutines Data |
| mexn | MATLAB NeXT Dynamically Linked Subroutines Data |
| mexrs6 | MATLAB IBM RS/6000 Dynamically Linked Subroutines Data |
| mexsg | MATLAB Executable |
| mexw32 | MATLAB Executable |
| mexw64 | MATLAB Executable |
| mf | Java Manifest File |
| Panda3D Gameplay Multifile |
| mfa | Multimedia Fusion Source |
| mfcribbon-ms | MFC Ribbon Resource |
| mfd | ABC Monadic Functions Data |
| mfl | Localized Managed Object Format File |
| mfo | Perl ModInfo Descriptor |
| mfps | MFP Script |
| mft | Crestron SIMPL Manifest Data |
| Java Manifest File |
| Origin Game Update Package Manifest |
| mfu | MobileFrame Update Package |
| mfv | MobileFrame Device Pack |
| mfw | MobileFrame Workflow Pack |
| mfx | Multimedia Fusion Extension |
| mg | Modula-3 Generic Module Source Code |
| mgr | WinDev Graphics Data |
| mi | WinAMP Maki Script |
| mimg | MCS Component Policy Editor Image Component |
| min | Freemacs Mint Source Code |
| mingw | MinGW Makefile |
| mingw32 | MinGW Makefile |
| mix | Power C Object |
| miz | Mizar Article |
| mjs | ECMAScript JavaScript Module |
| MongoDB JavaScript |
| mk | GNU Makefile |
| mkcd | MakeCode Program |
| ml | OCaml Source Code |
| mlapp | MATLAB Application Package |
| mlb | FoxPro 2 for Macintosh Library |
| mlc | Message Tools for NetWare Source Code |
| mld | WinDev Logical Data Model |
| mlh | Message Tools for NetWare Source Code |
| mli | OCaml Interface Source |
| mlib | MATLAB Shared Library |
| mlmodel | Create ML Model |
| mlnk | MCS Component Policy Editor Link Component |
| mlo | Beaglebone Prebootloader Image |
| mlua | MetaLua Source Code |
| mlv | LabVIEW Mathscript |
| mlw | WhyML Program |
| mly | OCaml Ocamlyacc Input Data |
| mlyt | MCS Layout Policy Editor Data |
| mm | Groff MM Format Source |
| Xcode Objective-C Program Source Code |
