| lxb | LXBatch Program |
| lxp | LXP Source Code |
| lzx | OpenLaszlo Web Application |
| m | BRIEF Macro Module |
| E Source Module |
| Limbo Interface Declaration Data |
| MATLAB Script |
| Mercury Source Code |
| Xcode Objective-C Implementation |
| m1s | Mach3 Macro |
| m2 | Modula-2 Software Development System RFX Data |
| Modula-2 Software Development System SYX Data |
| Modula-2 Source Code |
| m2o | Modula Fitted Modula2 Data |
| MSSQL-to-Oracle Profile Description Data |
| m3 | Modula-3 Source Code |
| m4 | M4 Macro File |
| m4m | SynDEx Makefile Macro |
| m4x | SynDEx Executive Macro |
| m51 | µVision Listing Data |
| m66 | µVision Listing Data |
| m6m | Mazatrol M640M NC Unit |
| mab | Markaby Script |
| mac | IAR System C-SPY Macro Definition Data |
| Microsoft Dynamics GP Macro Script |
| UltraEdit Macro |
| magik | Magik Source Code |
| mak | Visual Studio Makefile |
| make | Drush Makefile |
| Xcode Make File |
| makepp | Makepp Makefile |
| mako | Mako Template |
| mal | Yaskawa MPE720 v5 Application |
| manifest | Java Manifest File |
| map | Delphi Detailed Map |
| IAR System XLink Output Data |
| Visual Studio Linker Map Data |
| µVision Listing Data |
| mapsao | Aleph One Maps Data |
| mar | IBM WebSphere Business Modeler Process Model Template |
| markdn | Markdown Document |
| markdown | Markdown Document |
| mas | WebFOCUS Master File Description |
| master | ASP.NET Master Page |
| mat | MATLAB Matrix |
| matlab | MATLAB Script |
| matrix | MATLAB Matrix |
| mauc | MCS Component Policy Editor Audio Component |
| maz | Mazatrol Program |
| mb | MapBasic Source Code |
| mbac | MascotCapsule Resource Data |
| mbas | microBasic Source Code |
| mbo | MapBasic Compiled Object |
| mbrext | Mobirise Extension |
| mbs | Mailbag Assistant Script |
| mbx | MapBasic Program |
| mc | Modula-3 Intermediate Language Code |
| Sendmail M4 Configuration Source |
| Windows Message Compiler Input |
| mc6 | Microsoft C Makefile |
| mcd | WinDev Conceptual Data Model |
| mcf | Microsoft Shell Console Script |
| mcht | MCS Component Policy Editor Chart Component |
| mcl | microC Binary File |
| mcr | FactoryTalk View Studio Macro Component File |
| mcurl | Curl Manifest Data |
| mcw | MPLAB IDE Workspace |
| md | GCC Machine Description |
| mdb | Crestron SIMPL Device Database |
| ProWorx NXT Memory Data with Blocking |
| mdd | Database Designer for MySQL Database Diagram |
| mde | WinDev RAD Pattern Data |
| mdes | Trimaran Machine Description Language Data |
| mdf | FactoryTalk View Studio Data Log Model |
| ProWorx NXT Memory Data File |
| WinDev Internal Data |
| mdl | 3D Gamestudio Model Data |
| Valve Source Model Data |
| WinDev RAD Model Data |
| mdle | Motion Description Language Extended Data |
