.??_ Files ending in "_" are often compressed install files of the same
name (e.g., .EX_ expands to .EXE, .DL_ expands to .DLL, etc.)
.M Matlab Function
Brief Macro Source
Mathematica File
Limbo Interface Declaration (Inferno OS)
Cliq Accessories Datebook Modification File [Linux Suite PDF Description]
Desktop Color Separation Specification Magenta Layer (usually an EPS file)
.M_U MazeGold Critical File Backup
.M?? Ingres Modify Table/Index File (?? = Hex 00 to FF)
.M$S MindStor Firmware Update File (M$A$W.M$S)
.M11 MASS11 Text File
.M12 Proprietary Data Format for Interchange of Defense Form
Data with Mil-Pac Technology Software Products (link is PDF file)
S-BASIC File
Hydrographs Synthesis Project File
SHARP MZ-series Emulator File
.M15 Apple MPEG-1 Video
.M18 Accolade Golf Course File
.M1A Apple MPEG-1/2 Audio
.M1S MPEG Media File [Play with Quicktime]
.M1V MPEG-1 Video File
.M2A Apple MPEG-1/2 Audio
.M2P MPEG-2 Program Stream Format File
.M2S MPEG-2 Audio and Video (system stream)
.M2V MPEG-2 Video Only File
.M3 Modula 3 Program File
.M32 Dr.T MIDI File
.M3A MPEG Archive Enhanced .M3U Playlist File
.M3D 3D Animations Macro
Corel Motion 3D Animation
EverQuest File
.M3S Myst III Exile Saved Game
.M3U MP3 Playlist File [WinAmp] [MattBatt iAM-player]
.M3URL MP3 Playlist File [Used by Quicktime or Winamp]
.M4 UNIX M4 Preprocessor File
.M75 Apple MPEG-1 Video
.M8 Heretic II MipMap [XnView]
.MA Maya File (ASCII)
Diablo II Map File
.MA1 SKY Mobile Phone Icon/Ringtone
.MA3 Harvard Macro (Harvard Graphics taken over by Serif)
.MAC MacPaint Bitmap Graphic [XnView]
Macro (various)
.MACP MacPaint Bitmap Graphic [XnView]
.MAD Microsoft Access Module Shortcut  [Buy Office XP at Shop.Microsoft]
Game Movie File (unverified)
.MAF Microsoft Access Form Shortcut [Buy Office XP at Shop.Microsoft]
.MAG MPS Magro Paint System Graphic
Microsoft Access Diagram Shortcut [Buy Office XP at Shop.Microsoft]
MAGIchan Graphic [XnView]
.MAI VAX Mail
.MAIL NeoPlanet Mail Client (old)
.MAK Make File (compiler project file)
.MAL AvantGo Connect-compliant Server Configuration File
.MAM Microsoft Access Macro Shortcut [Buy Office XP at Shop.Microsoft]
.MAN Manual (often an ASCII text file)
Windows 2000 Mandatory User Profile (C:/DOCUMENTS AND SETTINGS/USERNAME/NTUSER.MAN)
.MANIFEST Microsoft Visual Stylesheet for Windows Forms (Text file)
.MAP Image
Server-side Image Map (allows one to map link locations in a Web graphic)
Color Palette
AccView Network Map
Atlas MapMaker Map
Manifold Map (GIS mapping info)
DIV Game Studio Map [XnView]
Fenix Map [XnView]
Ingres Termcap Mapping File
Poser 3D Map File
WorldCraft Quake/Half-Life Game Level File
Blood Game File Map
Duke Nukem Game Level Data File
...and many more games (too many to list)
Linker Map
Micrografx Picture Publisher Format Data
PROGNOSIS Map Document File
.MAPIMAIL Microsoft Outlook Express Mail File
.MAPISEND Microsoft MAPISEND File (unverified)
.MAQ Microsoft Access Query Shortcut [Buy Office XP at Shop.Microsoft]
.MAR Microsoft Access Report Shortcut [Buy Office XP at Shop.Microsoft]
VAX Macro Assembly Program
Bibliographic Data Format (usually .MRC)
.MAS Focus Master Data Definition
Microsoft Access Stored Procedures [Buy Office XP at Shop.Microsoft]
Lotus Freelance Graphics Smartmaster File
QuickCard File
.MAT Sound File
Pro/Engineer Material Properties File
Matlab Variables Binary File
Microsoft Access Table Shortcut [Buy Office XP at Shop.Microsoft]
Autodesk 3D Studio Max and Viz File
Poser 3D Pose File
ArcView Geocoding Matching Parameters File
Ox Object-Oriented Matrix Programming Language Matrix File
CRiSP Harvest File
.MAUD Sound File [Linux Player]
.MAV Microsoft Access View Shortcut [Buy Office XP at Shop.Microsoft]
.MAW Microsoft Access Data Access Page [Buy Office XP at Shop.Microsoft]
.MAX Kinetix's 3D Studio MAX Scene
Autodesk 3ds Max Scene File
Maximizer Contact & E-business Program
Paperport Scanned Image [Viewer]
Max Source Code
OrCAD Layout File
.MAZ Hover Maze Data
Division's dVS/dVISE File
.MB Paradox Memo Holder
Maya Binary (3D Software Maya Scenes)
.MB1 Apogee Monster Bash Data File
.MBD Multimedia Builder MP3 Authoring File
.MBF Microsoft Money Backup File
.MBFS Stardent AVS X Image [XnView]
.MBFAVS Stardent AVS X Image [XnView]
.MBG Mailbag Assistant E-mail Archive
.MBK dBase IV Multiple Index Backup
VersaPro Motion Block Backup
.MBM SymbianOS Multi BitMap Image (native EPOC image format) [XnView]
.MBS Mailbag Assistant Script
.MBT ecBuilder Template (Web site cataloging)
.MBU Neverwinter Nights Music File
.MBW MarketBrowser (investment charting/analysis)
.MBX Mailbox Message File (Outlook v1-4 or Eudora and others)
.MC MetaCard Script
PlaySaver and PSEmuPro Memory Card Save and Single Game Save
.MC1 MedCalc Data File (statistical research program)
.MC3 Bridge Design Modeler 3D Match-Casting Geometry Control
.MC7 Mastercam 7 File (CAD/CAM Geometry)
.MC8 Mastercam 8 File (CAD/CAM Geometry)
.MC9 Mastercam 9 File (CAD/CAM Geometry)
.MCA i-deas Web ACCESS File
.MCC Mathcad Configuration
Mylar City Character Editor
Dialer10 Calling Card
Monu-Cad Pro CAD File
VectorWorks/MiniCAD File [Viewer]
Incite Media Assistant File
.MCD Mathcad Document
Craig McDowall.com NotePad
Monu-Cad Pro CAD File
Bleem! Memory Card Save
.MCF Mathcad Font
Meta Content Format File (describes a Web site) [Process description]
Master Command File
TMPGEnc Template (Multimedia Container Format File)
.MCH Macromedia Xtra Cache File
.MCI Media Control Interface Command Set
.MCL Multimedia Manager Collection File
Macro Command Language (Symbol handheld terminals)
.MCP Mathcad Printer Driver
Capsule Application Script
Metrowerks CodeWarrior Project (Symbian application development)
.MCQ McAfee Quarantined File
.MCR DataCAD Keyboard Macro File
PlaySaver and PSEmuPro Memory Card Save and Single Game Save
CuteFTP Script
.MCS MathCAD Format File
.MCT Musicator
.MCW MacWrite II Macintosh Text File
.MCX Graphic File
.MD Compressed Archive File
Teknical eLearning Objects Meta-Data File (stores info on related file)
Technics Keyboard User MIDI Settings File
.MD1 Gear CD Suite File
.MD3 Quake 3 Arena Model File (Q3 only)
.MD5 MD5summer (generates and verifies md5 checksums) [MD5 Generator] [fsum Checksum Utility]
.MDA Microsoft Access Add-in
Microsoft Access 2 Workgroup
.MDB Microsoft Access Database
Microsoft Access Application
Mediator Multimedia Data
PTC Pro/MECHANICA File (test/optimize designs for structural,
dynamic, thermal and durability performance)
.MDE Microsoft Access MDE Database File
.MDF Menu Definition File
Microsoft-SQL Master Database File
Accelio Capture Classic (JetForm) Filler (JetForm Corp became Accelio 12 Sep 2001)
I-deas Master Drafting Machine Data File
Star Trek Armada Map File Title & Image Information (links .BZN File to Title and to custom .BMP)
Insight II Molecular Data File
.MDHTML Microsoft Access HTML File
.MDI Borland Multiple Document Interface
.MDL Digitrakker Music Module (by n-FaCToR)
Rational Rose
Quake Model File
3D Design Plus Model
Simulink Simulation Model
ASTi Model Builder File
CA-Compete! Spreadsheet
Half-life Model [XnView]
Moray Model (wireframe modeller supporting POV-Ray 3.1)
Symbian OS MIME Type Library
.MDM Telix Modem Definition
.MDMP WinXP Trouble Report (extension is added to file sent)
.MDN Microsoft Access Blank Database Template [Buy Office XP at Shop.Microsoft]
.MDO Microsoft Internet Information Server Configuration Backup
.MDP Microsoft Developer Studio Project
.MDR FaxTalk Modem Doctor Modem Report File
.MDS Media Description File [Fantom CD Emulator]
.MDT Microsoft Access Add-in Data [Buy Office XP at Shop.Microsoft]
Microsoft ILink Incremental Linker Data Table
.MDW Microsoft Access Workgroup Information [Buy Office XP at Shop.Microsoft]
.MDX dBase IV Multiple Index [File Structure]
Avery Label Pro Re-Index File
.MDZ Microsoft Access Wizard Template [Buy Office XP at Shop.Microsoft]
Protracker/Module File [use Winamp]
.ME Information (e.g., READ.ME)
.MEA Meazure File (screen measurement and capture utility)
.MEB WordPerfect Macro Editor Bottom Overflow File
.MED WordPerfect Macro Editor Delete Save
OctaMED Tracker Module
.MEL Ericsson Phone Melody
Maya Embedded Language Script
.MEM WordPerfect Macro Editor Macro
Memory File of Variables
Microsoft FoxPro Memory Variable Save File
.MEN Menu
.MEQ WordPerfect Macro Editor Print Queue
.MER WordPerfect Macro Editor Resident Area
Data Interchange Format
.MES Message File
WordPerfect Macro Editor Work Space
.MET WordPerfect Macro Editor Top Overflow File
Presentation Manager Meta File
OmniPage Document
eDonkey2000 File
.METHODS Likely a text file (e.g., README.METHODS)
.MEU DOS Shell Menus
.MEX Matlab Executable Command
WordPerfect Macro Editor Expound File
mexReader Multimedia File
.MEZ RealArcade Game Information
.MF MetaFont Text File
.MFA Microsoft Site Server 3.0 Report Definition
.MFD F1RC Relay Game Code File [Support site]
.MFF MIDI File Format
.MFG MediaForge Runtime Player
.MFM VTeX Multiple Master Font Metrics (a variant of the Adobe Font Metrics (AFM) format?)
.MGC MGCSoft Equation Editor File
.MGCF MagicInstall Compressed File
.MGD Master Grade Gradebook
.MGF Image File
Micrografx Font
Materials and Geometry Format File
.MGL MosASCII Graphics Library
Microsoft Age of Kings File
.MGM MGCSoft Equation Editor Macro File
.MGR MGR Bitmap [XnView]
.MGS Intelligence Tracking System File (Law Enforcement Data Collection)
.MGX Micrografx Picture Publisher Clipart
.MGZ Metal Gear Solid Archive [Dragon UnPACKer]
.MH Graphic File
.MHG Multimedia File
.MHK Riven Movie Data File (Mohawk Archive)
.MHP Microsoft Home Publishing Project
.MHT Microsoft MHTML Document (Archived Web Page)
.MHTML Microsoft MHTML Document (Archived Web Page)
.MI Miscellaneous
CoCreate CAD File
.MIB Management Information Base File (SNMP Management Programs)
.MIC Microsoft Image Composer File (shipped with FrontPage, no longer sold)
.MID MIDI File [IrfanView]
MapInfo Interchange Format (always paired with "MIF")
.MIDI MIDI File [IrfanView]
.MIF MIDI Instrument
Adobe FrameMaker Interchange Format
Software License Tracking Tool (CERTAUTH.MIF)
MapInfo Interchange Format File (always paired with "MID")
MicroHof .MIF Assembler File
Image Magick File [XnView]
.MIFF Image Magick File [XnView]
.MII MicroStat II Data File
.MIL Group 4 Fax File
Micro Illustrator Uncompressed Graphic [XnView]
.MIM Multi-Purpose Internet Mail Extensions (MIME) File [MIME] [WinZip should decode]
.MIME Multi-Purpose Internet Mail Extensions (MIME) File [MIME] [WinZip should decode]
.MIO mexReader Multimedia File
.MIP Paint Shop Pro Multiple Image Print File
.MIS Delta Force Land Warrior Mission [Fan site]
Tribes 2 Game File
MagicInstall Installation Script
.MIX Power C Object File
Multilayer Picture File (Microsoft PhotoDraw 2000 & Microsoft Picture It!)
Don Knuth's MIX Emulator
Command & Conquer Picture/Sound File
(series of .PCX images and .WAV sound) [Winamp plugins available to play] [Format]
Techno eJay Music Mix File
OzWin CompuServe E-mail/Forum Access Index File
.MIZ Winamp Compressed MIDI File
.MJ MovieJack DVD Ripper File
.MJF Mjuice Secure Music Files [use Winamp with Mjuice Secure MP3 Decoder]
.MK Make File
.MKD Malz++Kassner CAD5 Drawing
.MKE Make File
.MKI Picture File
.MKL Malz++Kassner CAD5 Drawing Library
Créatoria
.MKS Tact Data
.ML3 Milestones 3.x Project
.ML6 PowerPoint Milestone File
.MLB Macro Library
.MLD Multilizer Dictionary
Polyphonic Ringtone File for Phones
.MLI Encyclopedia Media List
3D Studio/AutoCAD Material-Library File
.MLK Sierra Mastercook File
.MLM Novel Groupwise E-mail File
.MLN AutoCAD Multiline Definition File
.MLS Miles Sound Tools Compressed DLS
.MM Macro Mania Macro
Multimate Advantage File
Lightscape Material Map
.MMB MultiMedia Builder
Oracle Forms Menu Binary Source Code
.MMC Media Catalog
Microsoft Office Media Content (Microsoft OfficeXP)
.MME Multi-Purpose Internet Mail Extensions (MIME) File [MIME]
.MMF Meal Master Format
Microsoft Mail File
Polyphonic Ringtone File for Phones
.MMI Memo Open Client
.MML Mail Meta Language
.MMM Animation Microsoft Multimedia Movie
MacroMind Directory RIFF/RMMP Format Movie
Adobe Multiple Master Font File
.MMO RapidFile Memo Writer
.MMP MindManager Map File
Gammadyne Mailer Project File
CoCo Systems VisiMap
Bravado Board Video Output Format
.MMPBT MindManager Branch Template File
.MMPT MindManager Template
.MMS Miles Sound Tools (Midi+DLS/MLS)
.MMSCRIPT MindManager Script File
.MMT Nimbus 7 SAMS Data File (monthly mean retrieved temperatures)
CoCo Systems VisiMap
.MMV Sony MovieShaker File
.MMW Microsoft Media Content
.MMX Command & Conquer Red Alert 2 Map File
Oracle Forms Compiled Menu
.MMZ MusicMatch Theme File
.MN2 Descent2 Mission File
.MN3 Descent3 Mission File
.MN4 Microsoft Money Database (older version)
.MNB MuPAD File
.MNC My Notes Center File
AutoCAD Compiled Menu File
.MND AutoCAD Menu Program File
MNI Mandelbrot for Windows
.MNG Animation Shop Animation
DeLorme Map'n'Go Map
Multi-image Network Graphic [XnView]
.MNL AutoCAD AutoLISP Functions Related to Menu
.MNO Monopoly Saved Game
Macromedia Design Notes
.MNR AutoCAD Compiled Menu File
.MNS AutoCAD ASCII Menu File
.MNT Foxpro Menu Memo
.MNU Menu File (various)
HP NewWave Advanced Macro
AutoCAD Menu Template File
.MNW Menu File (various)
.MNX AutoCAD Compiled Menu File
Foxpro Menu
.MNY Microsoft Money File
.MO Dymola Simulation
.MOB Device Definitions
.MOD Music File (various)
Model File (various)
Modula-2 Program File
ProModel Optimization Software Suite Model
Windows Kernel Module
Amiga and PC Tracker Module
Microsoft Multiplan Spreadsheet
Monarch File (data mining)
CATIA Export File [Dassault Systems] [IBM]
.MODEL CATIA File [Dassault Systems] [IBM]
.MOL MDL Molfile (MIME type chemical/x-mdl-molfile) [Requires Chime Plug-in]
Easy Palette Object Library
.MOM SPEFO Stellar Spectra Analysis File
.MON ReadMail Monitor (UNIX)
Virgin Games Monopoly Deluxe (Atari ST)
.MONO Bi-level Bitmap in Least-Significant-Byte First Order
.MONTE CRiSP Harvest File
.MOOV QuickTime Movie
.MOP Mopac Input File (MIME type chemical/x-mopac-input)
.MOR Poser 3D Morph Target File
.MOS Dymola Simulation
Infinity Game Engine Background and GUI Tile Info [More Info]
Compressed Infinity Game Engine Background and GUI Tile Info [More Info]
.MOT Phoneme Translation File
Linux Load Instructions (ASCII file)
.MOV QuickTime Video Clip [IrfanView]
AutoCAD AutoFlix Movie
.MOVERADDIN Mover (Inventory Management) Add-in
.MOVERBACKUP Mover (Inventory Management) Backup Set
.MOVERCONFIG Mover (Inventory Management) Configuration
.MOVERDB Mover (Inventory Management) Database
.MOVERREG Mover (Inventory Management) Registration Info
.MOVERTEMPLATE Mover (Inventory Management) Template
.MOVIE QuickTime Movie
.MOX Extend Simulation Model File
.MOZ Netscape Temp File
.MP Multiplan File
Maya Personal Learning Edition File
EARS Component File (EARS = UK Liberal Democrats Election Agents Record System)
[Filename starts with E]
.MP+ MpegPlus Audio File (replaced by .MPC)
.MP1 MPEG Audio Stream, Layer I
.MP2 MPEG Audio Stream, Layer II
.MP2V MPEG Audio Stream, Layer II
.MP3 MPEG Audio Stream, Layer III [IrfanView]
mp3PRO Audio File (enhanced MP3 format)
SHARP MZ-series Emulator File
Wrapster Wrapped File (hide any file in .MP3 format)
.MP4 iVAST MPEG-4 (hold BIFS-Binary Information For Scene representation) [MPEG-4 Industry Forum]
.MPA MPEG Audio Stream, Layer I, II or III
Palm Memo File
.MPB TruVideo Video-only MPB Stream [Win Media Player Plug-in]
.MPC Microsoft Project Calender
MP3 Collector Collection Manager File
VersaPro Compiled Motion Block
Musepack Audio File (new format replacing .MP+)
.MPCB ReliaSoft MPC 3 (MSG-3 Aircraft Maintenance Program Software)
.MPD SCSI MiniPort Driver
Microsoft Project Database File
.MPDEX MPdex MP3 Database Utility
.MPE MPEG Movie Clip
.MPE.EXE MP3 Digital Player Wrapper
.MPEG MPEG Movie
.MPF Microsoft Design Gallery
MosASCII Project Workspace File
.MPG MPEG Animation [IrfanView]
MPEG 1 System Stream
.MPG4 MPEG-4 Media File [Play with Quicktime]
.MPGA Mpeg-1 Layer3 Audio Stream
.MPH Microsoft Publisher
.MPJ RoboHTML Project
Mountain Video Editing File (Atari)
Sometimes .MP3 File
.MPK Augmented Microsoft-Project File
.MPM WordPerfect MathPlan Macro
Max Payne MOD Archive [Added Info]
MPEG Movie [Play with Quicktime]
.MPNT MacPaint Bitmap File [XnView]
.MPO Augmented Microsoft-Project File
.MPP Microsoft Project File
CAD Drawing File
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