| mdes | Trimaran Machine Description Language Data |
| mdf | FactoryTalk View Studio Data Log Model |
| mdf | ProWorx NXT Memory Data File |
| mdl | 3D Gamestudio Model Data |
| mdl | Valve Source Model Data |
| mdle | Motion Description Language Extended Data |
| mdmp | Windows Debug Dump |
| mdown | Markdown Document |
| mdp | Microsoft Developer Studio Project |
| mdx | IBM Rational XDE Model Data |
| mdx | Multidimensional Expressions Script |
| mea | FactoryTalk View Studio Project Backup |
| mec | Hitachi Ladder Editor Memo Comment |
| med | FactoryTalk View Studio Development Application |
| mediawiki | MediaWiki Source Code |
| mel | Autodesk Maya Embedded Language Script |
| 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 |
| mf | Panda3D Gameplay Multifile |
