| minder | Minder Mind Map |
| mjb | MuJoCo Binary Model |
| mjbooktemplate | MacJournal Book Template |
| mjcf | MuJoCo XML Model |
| mjdoc | MacJournal Document |
| mkd | CAD6 Drawing |
| mkd | MarkDown Document |
| mla | WorshipCenter Pro MLA Document |
| mlb | Lotus Symphony Macro Library |
| mli | Autodesk 3D Studio Material Library |
| mlj | Canon MultiPASS Suite Fax Document |
| mlk | MasterCook Look Data |
| mlm | Novell GroupWise Saved E-Mail |
| mlr | Mollier Sketcher Document |
| mls | WorshipCenter Pro MLS Document |
| mm | MultiMate Advantage II text document |
| mma | Master Album Maker Document |
| mmd | DocsAlive Multimedia Document |
| mml | Mathematical Markup Language Document |
| mmp | MindManager 2002 Map Document |
| mmpt | MindManager 2002 Map Template |
| mmsw | Movie Magic Screenwriter Document |
| mnb | MuPAD Notebook Document |
| mnc | My Notes Center Notebook |
| mnl | Help and Manual Print Manual Template |
| mnp | Ultrasoft Money Document |
| mny | Microsoft Money Data |
| money | Microsoft Money Data |
| montage | Montage Screenplay Document |
| mosaic | MacOSaiX Mosaic |
| mox | Montax Imposer Template Document |
| mpd | LDraw Multi-Part Document |
| mpf | Microsoft Media Package File |
| mpp | Microsoft Project Document |
| mps | Garmin MapSource Document |
| mpt | Microsoft Project Template |
| mpx | Microsoft Project Exchange Document |
| mrcx | MARC21 XML Schema |
| mrd | MathRevolt Ininity Document |
| mrml | 3D Slicer Scene Description |
| mrml | Medical Reality Modeling Language File |
| mro | SharpEye Music Reader Document |
| mrp | MathRevolt Ininity Plot |
| ms | Maple Worksheet |
| ms10 | NI Multisim 10 Circuit Design |
| ms11 | NI Multisim 11 Circuit Design |
| ms12 | NI Multisim 12 Circuit Design |
| ms13 | NI Multisim 13 Circuit Design |
| ms14 | NI Multisim 14 Circuit Design |
| ms3d | MilkShape 3D Model |
| ms7 | NI Multisim 7 Circuit Design |
| ms8 | NI Multisim 8 Circuit Design |
| ms9 | NI Multisim 9 Circuit Design |
| msc | MuseScore v1 Music Score |
| mscx | MuseScore Music Score |
| mscz | MuseScore Compressed Music Score |
| msd | Maxsurf Design |
| msg | Microsoft Outlook E-Mail Message |
| msim | MapleSim Model |
| msm | NI Multisim Circuit Design |
| msmx | Multisim Touch Circuit Design |
| mss | MuseScore Style Definition Data |
| mss | Perfect Writer Manuscript text |
| mst | NI Multisim Circuit Design Template |
| mst13 | NI Multisim 13 Circuit Design Template |
| mst14 | NI Multisim 14 Circuit Design Template |
| msw | Microsoft Word 5 Document |
| mswd | Microsoft Word for Mac Document |
| mswk | Microsoft Works for Mac Document |
| mtd | Musicnotes Digital Sheet Music |
| mtf | MasterCook Document |
| mtp | Minitab Portable Worksheet |
| mtp | Power Translator Document |
| mts | Viewpoint MTS Document |
| mud | Autodesk Mudbox Model |
| mug | Hanes T-Shirt Maker Document |
| mup | Music Publisher Score |
| musx | MakeMusic Finale Notation Document |
| mvd | MindView 5 for Mac Document |
| mvdx | MindView for Windows Document |
| mvs | Microchip Verification Specification Data |
| mvtx | MindView for Windows Template |
| mw | MacWrite Text Document |
| mw | Maple Standard Worksheet |
| mw2d | MacWrite II Document |
| mwd | Mariner Write Document |
| mwii | MacWrite II Text Document |
| mwk | Music Write Score Document |
| mwp | Lotus Wordpro Smartmaster File |
| mwpr | MacWrite Pro Document |
| mws | Maple Classic Worksheet |
| mwt | MetaStock Stock Analysis Template |
| mwz | Maple Compressed Worksheet |
| mxs | Maxwell Render Scene |
| mytx | MyThoughts for Mac Document |
| myv | Vivaldi Studio Music Score Document |
| myw | MyWorld Education Drawing Document |
| mz | MOZART Music Document |
| mzt | MOZART Score Template |
| n3 | Notation3 Document |
| nb | Mathematica Notebook File |
| nb | Nota Bene Document |
| nbk | WaveStar Notebook |
| nbml | Mathematica NotebookML File |
| nbp | Mathematica Player Notebook |
| ncd | Nero Cover Designer Document |
| ncd | NoteCase Pro Document |
| nce | NoteCase Pro Encrypted Document |
| nct | Nero Cover Designer Template |
| ncz | Netcad Drawing Document |
| ncz | NoteCase Pro Compressed Document |
| nd | Intuit QuickBooks Network Data File |
| ndb | MyDraw Binary Drawing Document |
| ndg | Network Notepad Network Diagram |
| ndo | Nendo Enhanced Native File |
| ndoc | Naver Word Document |
| ndtx | MyDraw XML Drawing Template |
| ndw | Nemetschek Allplan Document |
| ndx | MyDraw XML Drawing Document |
| ne3 | OM2 OMALI NENA Encrypted Document |
| nec | NEC-JIS Encoded File |
| neu | Pro/ENGINEER Neutral Assembly |
| nfd | Nefsis Document |
| nff | WorldToolKit Neutral File Format Data |
| nfo | Microsoft System Information File |
| nfo | NFO File |
| nft | NetObjects Fusion Template |
| ng | Norton Guide |
| ngdoc | AngularJS Document |
| ngloss | Nisus Writer Pro Glossary |
| nhb | Nero Burning ROM AVCHD-Video Compilation Data |
| nhf | Nero HFS CD Compilation |
| nhv | Nero HD-Burn Video Compilation |
| njx | NJStar Japanese WP Document |
| nlbl | NiceLabel Label |
| nld | Network Logic Diagram Document |
| nlx | FormWorx Form Document |
| nm5 | NovaMind 5 Mind Map Document |
| nmbtemplate | Numbers Spreadsheet Template |
| nmd | Nero MiniDVD Compilation |
| nmind | NovaMind 4 Mind Map Document |
| nms | Note-Mate Question Set |
| nmw | Netmeeting T126 Whiteboard Document |
| nof | NetObjects Fusion Document |
| not | E-Sword Notice |
| not | Veign Note-It Note |
| note | Notessimo Composition |
| npd | Netrosoft Presentation Document |
| npp | Art Explosion Publisher Pro Document |
| nr3 | Nero MP3 CD Compilation |
| nr4 | Nero AAC CD Compilation |
| nra | Nero Audio CD Compilation |
| nrb | Nero Boot CD-Rom Compilation |
| nrc | Nero UDF/ISO CD-Rom Compilation |
| nrd | Nero DVD-Video Compilation |
| nre | Nero CD Extra Compilation |
| nrh | Nero Hybrid CD-Rom Compilation |
| nri | Nero ISO9660 CD-Rom Compilation |
| nrm | Nero Mixed Mode CD Compilation |
| nrs | Nero CD-Rom (EFI Boot) Compilation |
| nru | Nero UDF CD-Rom Compilation |
| nrv | Nero VideoCD Compilation |
| nrw | Nero WMA CD-Rom Compilation |
| nsd | Nero Super VideoCD Compilation |
| nsln | NiceLabel Solution |
| nt7 | Orchida Knitting System Pattern |
| nta | Nota Aspel Document |
| nte | Asus EEE Note Document |
| ntg | New Tool Geometry File |
| ntp | MediaFACE CD Label |
| nts | Psion Organiser Notepad Document |
| ntt | MediaFACE Template |
| nud | Now Up-To-Date Calendar Document |
| num | Nashville Number System Chord |
| numbers | Numbers Spreadsheet File |
| numbers-tef | Apple Numbers iCloud Spreadsheet |
| nvc | Nero Vision Compilation |
| nvdl | NVDL Script |
| nwcp | Nisus Writer Pro Clipboard Document |
| nwd | NavisWorks JetStream Publisher Model |
| nwf | NavisWorks File |
| nws | Microsoft Internet News Message |
| nxl | Haansoft Nexcel Document |
| nxt | Haansoft Nexcel Template Document |
| nx__ | WriteNow 4 Document |
| nzb | Newzbin NZB Data |
| o2c | O2C 3D Model |
| o3m | Ortho 3D Model Document |
| oa2 | Fujitsu Oasys 2 Document |
| oa3 | Fujitsu Oasys 3 Document |
| oad | Notaro Document |
| oas | Fujitsu Oasys Document |
| obd | Microsoft Office Binder Document |
| obm | EIAS Camera Motion Export |
| obml | Opera Binary Markup Language Document |
| obo | OBO-Edit Document |
| obp | Bryce 3D Model |
| obt | Microsoft Office Binder Template |
| obx | OpenBook v8 Document |
| obz | Microsoft Office Binder Wizard |
| ocd | Orgadata LogiKal CAD Drawing |
| ocdc | Mathematica Document |
| ocf | GstarCAD Drawing |
| ocg | Osprey Custom Graph |
| ocr | FAXGrapper Fax Text |
| ocr | RelayFax OCR Document |
| odb | OpenOffice.org Base Database |
| odc | OpenDocument Chart |
| odf | OpenDocument Formula |
| odm | OpenDocument Master Document |
| odo | Online OS Write Document |
| odp | OpenDocument Presentation |
| ods | OpenDocument Spreadsheet |
| odt | OpenDocument Text |
| odtpc | Oracle UPK Presentation |
| ofc | Open Financial Connectivity Document |
| ofs | Microsoft Outlook Form Storage |
| oft | Microsoft Outlook Template |
| ofx | Open Financial Exchange Document |
| ol | PTC Creo Model File |
| olf | OyezForms Legal Document |
| olfx | OyezForms 10 Document |
| oli | Olivetti Text Document |
| olv | OyezForms Legal OLV Document |
| om | Configura Drawing Document |
| omd | MindView for Mac Document |
| oml | TracePro Model |
| omp | OpenMind Document |
| omv | Jamovi Document |
| onb | OpenModelica Notebook |
| one | docPointer Visual ReadMe Data |
| one | Microsoft OneNote Document |
| oo3 | OmniOutliner 3 Document |
| oo3template | OmniOutliner 3 Document Template |
| oogl | Object Oriented Graphics Library |
| oos | OpenOffice.org Spreadsheet |
| oot | OpenOffice.org Text |
| opd | OmniPage Document |
| opeico | Opeico Text Data |
| openbsd | OpenBSD related Readme Text |
| oplx | OmniPlan Document |
| opml | Outline Processor Markup Language File |
| opsx | Open Pedigree Standard Exchange Document |
| opt | PhotoScore Document |
| opw | OrgPlus Organization Chart |
| opx | Microsoft Organization Chart Document |
| opxt | OrpPlus Template |
| oqy | Microsoft Excel OLAP Query |
| or5 | Lotus Organizer 5 Document |
| or6 | Lotus Organizer 6 Document |