#_M_EXTENSIONS

.M    MATLAB file.
.M    Memo file.
.M    Merged file.
.M    Octave script file (Michael Margraf QUCS/Quite Universal Circuit Simulator).
.M15  MPEG video/audio stream (QuickTime 7.7.2).
.M1A  MPEG video/audio stream (QuickTime 7.7.2).
.M1S  MPEG video/audio stream (QuickTime 7.7.2).
.M1V  Moving Picture Expert Group, MPEG-1 video file (Many applications).
.M1V  MPEG elementry Video stream (DVDAuthor GUI).
.M1V  MPEG video/audio stream (QuickTime 7.7.2).
.M2   Modula 2 file = text/code.
.M2TS BluRay Disc media video (Many applications).
.M2V  MPEG elementry Video stream (DVDAuthor GUI).
.M3   MoviePack animation file (AIST MoviePack/MovieDV/MovieXone).
.M3A  MPEG audio file (Many applications).
.M3A  MoviePack Album file (AIST MoviePack/MovieDV/MovieXone).
.M3DANIM Transition animation file (Ashampoo Burning Studio).
.M3T  MoviePack animation Transition file (AIST MoviePack/MovieDV/MovieXone).
.M3U  Playlist file (Audio players).
.M3U  SMIL (QuickTime 7.7.2).
.M3U8 Playlist file in UTF-8 Unicode format = more appropriate for shared audio given it's capability to support any language's codepage/texts (Audio players).
.M3URL SMIL (QuickTime 7.7.2).
.M3W  MoviePack Workspace/Project settings file (AIST MoviePack/MovieDV/MovieXone).
.M4A  AAC audio (QuickTime 7.7.2).
.M4A  AAC/Advance Audio Coding format audio file (many applications).
.M4B  AAC audio book (QuickTime 7.7.2).
.M4B  Myst 4 Bin file = container/archive (UbiSoft's Myst 4 Revelation).
.M4O  Myst 4 game Options file (UbiSoft's Myst 4 Revelation).
.M4P  AAC Protected audio file (QuickTime 7.7.2).
.M4S  Myst 4 Save game file (UbiSoft's Myst 4 Revelation).
.M4V  MPEG-4 video file (Apple's QuickTime Player).
.M75  MPEG video/audio stream (QuickTime 7.7.2).
.MAC  MacPaint image (QuickTime 7.7.2).
.MAC  Monkey's Audio lossless format.
.MAF  Microsoft Access Form shortcut file (Microsoft Access 2002).
.MAG  Microsoft Access Diagram shortcut file (Microsoft Access 2002).
.MAGNET Magnet file and hash links file (Filesharing applications).
.MAK  Make file (Many programming development environments).
.MAKE Make file (Many program development environments, program compilers/lexical analysers, etcetera).
.MAKEFILE Makefile file.
.MAM  Microsoft Access Macro shortcut file (Microsoft Access 2002).
.MAN  Man/Manual page file (Many operating systems, applications and variations).
.MAP  Character Map or Mappings file (Many applications).
.MAP  Color Map filter (Many graphic image processing applications).
.MAP  Half-Life/Torque Map file (Leadwerks 3D World Studio, many applications/games, many variants).
.MAP  Template Map file (Microsoft's Office XP).
.MAQ  Microsoft Access Query shortcut file (Microsoft Access 2007).
.MAR  Microsoft Access Report shortcut file (Microsoft Access).
.MAS  Microsoft Access Stored procedure shortcut file (Microsoft Access 2002).
.MAT  Materials file (Bryce and other editors, games, simulators).
.MAT  Microsoft Access Table shortcut file (Microsoft Access).
.MAU  Microsoft Access URL shortcut file (Microsoft Access).
.MAV  Microsoft Access View shortcut file (Microsoft Access 2002).
.MAW  Microsoft Access Web data access page shortcut file (Microsoft Access).
.MBD  Multimedia Builder file (MediaChance Real-DRAW).
.MBK  Mamut web site project Backup file (Mamut Limited's Mamut).
.MBL  MusicBee Library file (Steven Mayall's MusicBee).
.MBM  Multi-resolution Bitmap image file.
.MBS  Micrografx Brush Shape file (Micrografx Picture Publisher).
.MCF  TMPGEnc Configuration File (Hiroyuki Hori's TMPGEnc/TMPGEncoder 2).
.MCR  Macro file (Arcsoft's Photo Studio 2000).
.MCW  Macintosh Word document file (Microsoft Word for Macintosh, many variants).
.MD3  Quake3 Model file (Quake3 game engine).
.MD5  Message-Digest algorithm 5 checksum file (Digital Extremes & Epic Games Unreal Tournament update 2003/UT2003).
.MD5  Message-Digest algorithm 5 checksum file = 32 character hexadecimal file/data hash/hashes (Many applications, especially data/file transmission and integrity verification).
.MDA  Add-in file (Microsoft Access).
.MDB  Microsoft Access Database (Microsoft Access and many database capable applications).
.MDBHTML Microsoft Access HTML document file (Microsoft Access).
.MDE  MDE database file (Microsoft Access).
.MDF  Alcohol 120% image file (Power Software's Free Any Burn).
.MDF  Alcohol 120% image file (Alcohol 120%).
.MDL  Model file (various games, environment simulators, etc.).
.MDN  Microsoft Access New/empty Database template file (Microsoft Access).
.MDS  Alcohol 120% image file (Power Software's Free Any Burn).
.MDT  Add-in Data file (Microsoft Access).
.MDW  Microsoft Access Wordgroup file (Microsoft Access).
.MDX  Multiple Index file (Ashton Tate's dBase and many other database applications).
.MDX  Music Director Mix file (eJay Music Director).
.MDZ  Microsoft Access Databae Wizard template file (Microsoft Access).
.MEDTHEME Movie Editor Theme file (Ashampoo Burning Studio 11).
.MEF  Meta Export File (MediaChance Real-DRAW).
.MEL  Maya Embedded Language geometry file (Maya and other animation/compositing applications).
.MER  Mercury Mail template file (David Harris' Mercury Mail).
.MESH Mesh model file (Ogre3D, Ogre Meshy).
.MET  Metafile (Many variants/applications).
.MF   Manifest (Many applications).
.MF   Metafile (Many applications).
.MF   Meta-INF file (Many applications).
.MFP  Macromedia Flash Paper file (Macromedia Flash).
.MFX  OpenFX model file (OpenFX).
.MGA  MPEG audio file.
.MGC  Graphics Collection database file (Microsoft Clip Organiser 2002).
.MGD  Gradiants file (Many applications).
.MGD  Microangelo Gradient file (Microangelo Suite).
.MGF  MotionGIF file (Wisdom-soft's MotionGIF).
.MGL  MotionGIF library file (Wisdom-soft's MotionGIF).
.MGX  Micrografx format clipart file (Micrografx Designer).
.MID  MIDI (QuickTime 7.7.2).
.MID  Musical Instumental Digital Interface file (Audio/sequencing applications and players).
.MIDI MIDI (QuickTime 7.7.2).
.MIDI Musical Instumental Digital Interface file (Audio/sequencing applications and players).
.MIF  Image File (FrameMaker).
.MIF  Morph Input File for font development and modification = plain text markup/data with escape codes (Apple's Font Tools).
.MIM  MIME-encoded file (Archivers, Usenet newsreaders, browsers, and other applications).
.MIME MIME-encoded file (Archivers, Usenet newsreaders, browsers, and other applications).
.MIS  Reporter Mission file (FirstPlace Software's WebPosition Gold).
.MIX  Color Mixer file (Pixel Studio Pro).
.MIX  MIX archive file (Westwood Studios' Command and Conquer).
.MKA  Matroska Audio file (Many audio applications).
.MKS  Matroska Sub-titles file (Aegisub).
.MKS  Matroska Sub-titles file (Many media player/editor applications).
.MKV  Matroska Video file (Many video applications).
.ML   Lisp source code file.
.ML   Mathematical Language file (Lisp and other mathematical programming languages).
.MLB  MIDI Library file (Willow Anvil Studio 2012).
.MLI  Material file (Autodesk 3DStudio Max and other applications).
.MLP  MeshLab Project file (Visual Computing Lab - ISTI - CNR's MeshLab).
.MM   Mindmapping file (Freeplane 1.1).
.MMD  MusicMatch Database file (MusicMatch Jukebox 3.x).
.MME  Library file (AIST MoviePack/MovieDV/MovieXone).
.MME  MIME-encoded file (Archivers, Usenet newsreaders, browsers, and other applications).
.MMG  MKVmerge GUI settings (MKVToolNix).
.MMI  Library file (AIST MoviePack/MovieDV/MovieXone).
.MMJB_MIME MusicMatch Jukebox mime file (MusicMatch Jukebox).
.MML  MathML formula file (MathML v1 enabled software).
.MMM  Multiple Master Metrics file (Many font/printing applications).
.MMP  Virtual Memory Map/VMMap log file (Sysinternals' VMMap utility).
.MMS  Multimedia Script file = text-based markup (MediaChance Real-DRAW).
.MMS  Skin file (AIST MoviePack/MovieDV/MovieXone).
.MMW  Plug-in file (AIST MoviePack/MovieDV/MovieXone).
.MMZ  MusicMatch extension file (MusicMatch Jukebox).
.MNG  Multiple-image Network Graphics animation file (Many applications).
.MNT  Menu memo file (Microsoft Visual FoxPro 6).
.MNU  Menu file (BDedit).
.MNU  Menu file (form-Z RadioZity).
.MNX  Menu file (Microsoft Visual FoxPro 6).
.MNY  Money database file = MS/Microsoft ISAM format (Microsoft Money).
.MO3  Mod file that contains MP3/OGG encoded samples (Ian Luck's XMPlay module/mod player).
.MOBI Mobipocket document file (Document/eReader viewers/editors).
.MOD  Model file.
.MOD  Module file (Many applications).
.MOD  Multiplan binary format file (Microsoft Multiplan 4.x).
.MOD  ProTracker Module audio file (Many Audio applications).
.MODULE Plug-in Module file (Timothy M Shead's K-3D 0.8).
.MOV  QuickTime movie (Apple's QuickTime Player).
.MOVIE Flash Movie project file (Insane Tools' 3D Flash Animator 3).
.MP1  MPEG 1 audio file (Many applications).
.MP2  MPEG 2 audio file (Many applications).
.MP2  MPEG video/audio stream (QuickTime 7.7.2).
.MP3  MPEG Layer-3 audio file (Many applications).
.MP4  AAC/Advance Audio Coding format audio file (Apple QuickTime Player).
.MP4  MPEG-4 video or audio (many applications).
.MPA  MPEG video/audio stream (QuickTime 7.7.2).
.MPC  MusePack audio file.
.MPCPL Media Player Classic playlist (plaintext).
.MPD  mp3DirectCut project file (Martin Pesch's mp3DirectCut).
.MPEG MPEG video with NAV packets (DVDAuthor GUI).
.MPEG MPEG video/audio stream (QuickTime 7.7.2).
.MPF  Media Package File (Microsoft Office).
.MPG  MPEG video with NAV packets (DVDAuthor GUI).
.MPG  MPEG video/audio stream (QuickTime 7.7.2).
.MPM  MPEG video/audio stream (QuickTime 7.7.2).
.MPR  Menu Program file (Microsoft Visual FoxPro 6).
.MPS  Max Payne game Save files (Max Payne).
.MPV  MPEG elementry Video stream (DVDAuthor GUI).
.MPV  MPEG video/audio stream (QuickTime 7.7.2).
.MQV  QuickTime movie (QuickTime 7.7.2).
.MRK  Drawing Markup file (AutoDWG's DWGSee).
.MRW  Minolta RAW format image file. (Many variants).
.MSG  Outlook e-mail Message file (Microsoft Outlook/Outlook Express).
.MSI  Microsoft Software Install file (Many application installers).
.MSJS Microsoft J# file (Microsoft VisualJ# "JSharp").
.MSK  Bitmap image file (Microsoft Visual FoxPro).
.MSL  MASS Synthesizer Layout file (MASS/Modular Analogue Software Synthesizer).
.MSM  Microsoft Software Merge module file (Many developer applications and software developer kit/SDK distributions).
.MSP  Clipart image file (IBM Crayola Print Factory).
.MSP  Microsoft Paint image file (Microsoft Windows operating system).
.MSP  Music Studio Project file (Magix Music Studio 6).
.MSS  MotionGIF MSS file (Wisdom-soft's MotionGIF).
.MSSTYLES Microsoft Visual Styles.
.MST  Master file (Corel Word Perfect Office Presentations).
.MST  MindSpring Template file (MindSpring Internet Desktop 3).
.MSWMM Microsoft Windows MovieMaker file (Microsoft Windows MovieMaker).
.MT6  Microangelo Toolset version 6 resource archive (Microangelo Studio).
.MTS  Metastream file (MetaCreations Canoma).
.MTW  Terrain file (Martin Wright's CFS TMap = Combat Flight Simulator Terrain Map editor).
.MV3  Lava animation scene file (Creative Technologies Lava Player).
.MVB  MicroVision Background image file contains a single PNG, JPEG, or WMF image (MicroVision SureThing CD Labeler).
.MVB  Multimedia Viewer file (Microsoft Multimedia Viewer).
.MVD  Muvee Descriptor file (Muvee Technologies' Muvee AutoProducer).
.MVE  Muvee project/document file (Muvee Technologies' Muvee AutoProducer).
.MVH  Muvee HTML file = HTML (Muvee Technologies' Muvee AutoProducer).
.MVO  Movie Organizer project file (OXD Software's Movie Organizer).
.MVP  Moving Path file (Ulead Systems Media Studio 5 Video Editor).
.MWM  Mech Warrior Mission file (Activision Mech Warrior 2).
.MXB  System Backup file (Ontrack Fix-It Utilities 3).
.MXML Flex source code file.
.MXR  Registry/Registy hive Backup file (Ontrack Fix-It Utilities 3).
.MXT  Mext file (SoftConstructors' StroyCode 1.28).
.MYD  MyDefrag script file (Jeroen Kessels' MyDefrag).
.MYD  MySQL MYD file (Many applications).
.MYD  MySQL MYI file (Many applications).

#_L_EXTENSIONS

.L    Lisp source code file.
.LA1  Liquid Audio v1 file (Liquid Audio Player and other media players).
.LAB  Mailing Label definition file (WordPerfect Office Suite).
.LAR  Liquid Audio Registration file (Liquid Audio Player).
.LASSO Lasso file.
.LATEX LaTeX file.
.LAV  Liquid Audio Voucher file (Liquid Audio Player).
.LAVS Liquid Audio Secure Voucher file (Liquid Audio Player).
.LAY  Layout file (MindScape PrintMaster Gold).
.LAY  Layout file (Pixel Studio Pro).
.LAY  Layout file = XML markup that provides MAME with instructions as to where resources are to be allocated for the ROM/application/game/etcetera associated/packaged with the LAY file and/or the MAME application (MAME).
.LB   Library file.
.LBI  Library file (Macromedia Dreamweaver).
.LBL  Label file (Microsoft Visual FoxPro 6).
.LBL  Label project file (MindScape PrintMaster).
.LBM  Deluxe Paint image file (Many applications).
.LBT  Label file (Microsoft Visual FoxPro 6).
.LBX  Label Extension definition file (Microsoft Visual FoxPro 6).
.LCD  CDSpace Image file (Power Software's Free Any Burn).
.LCD  L-Signature Cache Data file (Analinx Duplicatch).
.LCS  Lotus iCalendar file (Lotus Development's Lotus Organizer).
.LCT  Component Template file (Firehand Ember).
.LDB  Temporary Link Database file (VSoft's VideoClick Personal).
.LET  Letterhead project file (MindScape PrintMaster).
.LEV  Game level file (Many games).
.LEVEL Game level file (Many games).
.LEX  Dictionary file (Microsoft Office).
.LFF  LFF font file (LibreCAD).
.LFM  Delphi application resource file.
.LGC  XML/SGML Logic file (Corel Word Perfect Office X6).
.LGPL GNU Lesser General Public License file = license text (Many applications/distributions).
.LI   List file (Many applications).
.LIB  Sound Libraries file (eMagic SoundDiver).
.LIBRARY Library file (Ian Luck's XMPlay module/mod player).
.LIBRARY~ Temporary Library file (Ian Luck's XMPlay module/mod player).
.LIC  Licensing information/documentation in plaintext (Software distributions).
.LIC  Product activation License file = a file purchased by a user, usually on the world wide web, that activates a software product and/or enables the product to operate with all available features functional (Many applications).
.LIN  LineStyles file (CorelCAD).
.LIS  List file (Many applications).
.LISP Lisp programming language application or source code file.
.LIST List file (Many applications).
.LML  Songlist file (Bremmers Audio Design's Multitrack Studio).
.LNG  Application Language translation/localization file (Many applications).
.LNG  Language package file (UltraDefrag).
.LNGC Language/localization file (Steven Mayall's MusicBee).
.LNS  LinkStash bookmark or backup file (XRayz' LinkStash).
.LNX  Commodore Lynx chained files archive (Commodore emulator applications).
.LNX  Will Corley's LYNX format file = Files and their significant parameters sequentially packed/linked into a single container/archive file (Commodore computer emulation programs).
.LOCK Lock file (Axure RP Pro).
.LOG  Log file (Many operating systems, applications, and variations though usually plain-text-based files).
.LOGHARD ZCAD LOGHARD log file (Andrey M. Zubarev's ZCAD).
.LPAQ LPAQ archive file (Many variants and applications).
.LPAQ8 LPAQ8 archive file = PAQ and it's many variants are all brute force compression methods (PeaZip and other archive file applications).
.LPD  Launch Pad settings file (Helix' Nuts & Bolts).
.LPI  LodePaint Image file (Lode Vandevenne's LodePaint).
.LPL  Plug-in file (AceHTML Pro).
.LQP  Liquid Passport file (Liquid Audio Player).
.LQT  Liquid Text file (Liquid Audio Player).
.LR   Lode Runner game levels container.
.LRG  xRes LRG image file.
.LRS  Language Resource File (Corel Word Perfect Office X6).
.LSA  Liquid Skin Add-on file (Liquid Audio Player).
.LSI  XML/SGML Layout file (Corel's Word Perfect Office X6).
.LSP  Lisp source code file.
.LSP  XLisp script file.
.LST  Adobe font List file = Markup.
.LST  Backup files list file (Ontrack Fix-It Utilities 3).
.LST  List file (Ari Pikivirta's Home FTP Server).
.LST  Playlist file (Nic Wilson's MoviePlay 2.5 and other media players).
.LST  Structured notes List file (MemPad).
.LT   Language Translation file (Many applications).
.LTH  Letterhead document file (Sierra On-Line's Print Artist 3).
.LTX  LaTeX file.
.LUA  Lua programming language script file (UltraDefrag).
.LUA  LUA source code file.
.LUAR Lua programming language report file (UltraDefrag).
.LUT  Lutcurve values file (Atrise Lutcurve).
.LVL  Game level file (Many games).
.LVL  Levels filter settings file (Adobe System's Premiere 5).
.LW   LightWave binary Object file (NewTek LightWave Studio).
.LWO  LightWave binary Object file (NewTek LightWave Studio).
.LWS  LightWave Scene file (NewTek LightWave Studio).
.LWV  Linguistically enhanced WAV file (Microsoft Windows).
.LXO  LightWave object or Modo file (Many applications).
.LYRICS Lyrics file (Steven Mayall's MusicBee).
.LZMA LZMA archive file (SmithMicro's Stuffit Deluxe/Expander and other archive applications).
.LZP  LazPaint image file (Circular & Fabien Wang's LazPaint 4).

#_K_EXTENSIONS

.K3D  K-3D 3D project file (Timothy M Shead's K-3D 0.8).
.K3G  Video file (Mobile phones).
.KAOS KAOS Diagram file (KAOS).
.KAL  Kaliopa Orinj session file (Kaliopa Orinj 2.2.1).
.KAR  Karaoke file (Jan Fabirkiewicz' SingOutStrong Karaoke Player and many others).
.KAR  Karaoke file = MIDI format file (Many applications).
.KAR  MIDI (QuickTime 7.7.2).
.KBS  BASIC program Source file = plaintext (basic256.org's BASIC 256).
.KCHMVIEWER KCHMViewer document configuration file (KCHMViewer).
.KDC  Kodak Digital Camera file (Jasc Paint Shop Pro and other graphics applications).
.KEY  Encryption Key file (Jim the Standing Bear's Jim's Encryptor Decryptor).
.KEY  Key file (Many applications, many variants).
.KEY  Keyboard file = keystrokes recorded to a text file = batch file (Many applications, many variants).
.KEY  Product registration Key file (Greatis' RegRun Security Suite 3, Elaborate Bytes CloneDVD 2, many other applications).
.KEY  Registry Key entries - a binary file equivalent to Windows .REG file (Windows Registry Editor - REGEDIT.EXE).
.KEYS Keyboard file = keystrokes recorded to a text file = batch file (Many applications, many variants).
.KF   NetImmersive/Gamebryo animation file (NifTools NifSkope).
.KFA  NetImmersive/Gamebryo Animation file (NifTools NifSkope).
.KFM  NetImmersive/Gamebryo animation Manager file (NifTools NifSkope).
.KLN  Kloon file (Moor Computer Productions' Kloon).
.KNT  KeyNote file (BauerApps RightNote).
.KOMODOPROJECT Komodo Project File (ActiveState's Komodo Edit).
.KOMODOTOOL Komodo Tool file (ActiveState's Komodo Edit).
.KPF  Komodo Project File (ActiveState's Komodo Edit).
.KPL  Kazaa Playlist file (Kazaa Media Desktop).
.KPR  KPresenter Presentation file (KPresenter, Calligra Stage and other Presentation editors/viewers).
.KPT  KPresenter Presentation Template file (KPresenter, Calligra Stage and other Presentation editors/viewers).
.KPZ  Komodo Package file (ActiveState's Komodo Edit).
.KQP  Konica Quality Photo file (Konica brand devices, VidFun).
.KRA  Krita image project file (Krita).
.KRA~ Temporary file (Krita).
.KSF  Komodo Color Scheme File (ActiveState's Komodo Edit).
.KSH  Korn Shell script file (Unix/Linux-based operating systems employing David Korn's shell/command line interface/CLI).