| .INI | Microsoft Corporation | Innstillingsfiler | Windows Initialization File | Microsoft Windows | Microsoft Corporation |
| .INS | Open Source | Datafiler | LaTeX Installer Script | Microsoft Windows | Microsoft Corporation |
| .INV | Copyboy | Spillfiler | INVedit File | Microsoft Windows | Microsoft Corporation |
| .IN_ | Microsoft Corporation | Innstillingsfiler | Microcoft Setup Information Data | Microsoft Windows | Microsoft Corporation |
| .IPI | Microsoft Corporation | Eksekverbare filer | Microsoft Windows Installer Data | Microsoft Windows | Microsoft Corporation |
| .ISC | Xilinx, Inc. | Utviklerfiler | Xilinx Device Configuration File | Microsoft Windows | Microsoft Corporation |
| .ITS | Open Source | Lydfiler | Impulse Tracker Sample | Microsoft Windows | Microsoft Corporation |
| .JPN | Microsoft Corporation | Systemfiler | Windows Japanese Noise-Word List File | Microsoft Windows | Microsoft Corporation |
| .JQX | Microsoft Corporation | Datafiler | Microsoft Windows Help-Related File | Microsoft Windows | Microsoft Corporation |
| .KOR | Epic Games | Spillfiler | Unreal Engine Language Localization | Microsoft Windows | Microsoft Corporation |
| .LCN | Microsoft Corporation | Krypterte filer | License File | Microsoft Windows | Microsoft Corporation |
| .LGA | Microsoft Corporation | Datafiler | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGC | Microsoft Corporation | Datafiler | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGD | Microsoft Corporation | Datafiler | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGF | Microsoft Corporation | Datafiler | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGG | Microsoft Corporation | Datafiler | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGH | Microsoft Corporation | Datafiler | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGJ | Microsoft Corporation | Datafiler | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGM | Microsoft Corporation | Datafiler | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGN | Microsoft Corporation | Datafiler | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGP | Microsoft Corporation | Datafiler | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGS | Microsoft Corporation | Datafiler | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGX | Microsoft Corporation | Systemfiler | Microsoft Windows Received Message Data | Microsoft Windows | Microsoft Corporation |
| .LIBRARY-MS | Microsoft Corporation | Systemfiler | Windows Library Description File | Microsoft Windows | Microsoft Corporation |
| .LNK | Microsoft Corporation | Systemfiler | Windows File Shortcut | Microsoft Windows | Microsoft Corporation |
| .LOCAL | Embarcadero Technologies | Innstillingsfiler | Delphi User-Specific Project Options | Microsoft Windows | Microsoft Corporation |
| .MAILABVIEW | Microsoft Corporation | Datafiler | MS AddressBook File | Microsoft Windows | Microsoft Corporation |
| .MAN | Unknown Developer | Tektfiles | Unix Manual | Microsoft Windows | Microsoft Corporation |
| .MANIFEST | Microsoft Corporation | Systemfiler | Windows Application Manifest File | Microsoft Windows | Microsoft Corporation |
| .MAPIMAIL | Microsoft Corporation | Systemfiler | Send To Mail Recipient | Microsoft Windows | Microsoft Corporation |
| .MFI | Microsoft Corporation | Datafiler | Windows 98 Resource Kit Data Format | Microsoft Windows | Microsoft Corporation |
| .MFT | Kaspersky Lab | Datafiler | Kaspersky File Table | Microsoft Windows | Microsoft Corporation |
| .MLC | Microsoft Corporation | Systemfiler | Microsoft Language Interface Pack | Microsoft Windows | Microsoft Corporation |
| .MM4 | Microsoft Corporation | Tektfiles | Microsoft Windows Word Processing Format | Microsoft Windows | Microsoft Corporation |
| .MOF | Microsoft Corporation | Innstillingsfiler | Managed Object Format File | Microsoft Windows | Microsoft Corporation |
| .MS-WINDOWS-STORE-LICENSE | Microsoft Corporation | Datafiler | Microsoft Windows License Manager Data | Microsoft Windows | Microsoft Corporation |
| .MSD | ESRI | GIS-filer | Map Service Definition File | Microsoft Windows | Microsoft Corporation |
| .MSN | Microsoft Corporation | Innstillingsfiler | Host Blocking File | Microsoft Windows | Microsoft Corporation |
| .MSO | Microsoft Corporation | Datafiler | Microsoft Organization Chart Data File | Microsoft Windows | Microsoft Corporation |
| .MSRCINCIDENT | Microsoft Corporation | Uvanlige filer | Microsoft Windows Remote Assistance Request Data | Microsoft Windows | Microsoft Corporation |
| .MSSTYLES | Microsoft Corporation | Systemfiler | Windows XP Style | Microsoft Windows | Microsoft Corporation |
| .MSU | Microsoft Corporation | Systemfiler | Windows Vista Update Package | Microsoft Windows | Microsoft Corporation |
| .MS_ | Microsoft Corporation | Backupfiler | Microsoft Windows WinHelp Compressed Data | Microsoft Windows | Microsoft Corporation |
| .MUM | AmsterCHEM | Datafiler | MATLAB Unit Operation Model File | Microsoft Windows | Microsoft Corporation |
| .MVA | Microsoft Corporation | Komprimerte filer | Microsoft Setup Archive | Microsoft Windows | Microsoft Corporation |
| .MYDOCS | Microsoft Corporation | Systemfiler | Send To My Documents | Microsoft Windows | Microsoft Corporation |
| .NGR | NEPLAN AG | Datafiler | NEPLAN Graphic Data | Microsoft Windows | Microsoft Corporation |
| .NLD | ATI Technologies | Systemfiler | ATI Radeon Video Driver File | Microsoft Windows | Microsoft Corporation |
| .NLS | Uri Wilensky | Utviklerfiler | NetLogo Source Code File | Microsoft Windows | Microsoft Corporation |
| .NT | Microsoft Corporation | Systemfiler | Windows NT Startup File | Microsoft Windows | Microsoft Corporation |
| .NTF | Open Source | Fontfiler | Windows Font File | Microsoft Windows | Microsoft Corporation |
| .OC_ | Microsoft Corporation | Komprimerte filer | Compressed ActiveX Control File | Microsoft Windows | Microsoft Corporation |
| .OEM | Microsoft Corporation | Innstillingsfiler | Original Equipment Manufacturer Setup File | Microsoft Windows | Microsoft Corporation |
| .OLE | Microsoft Corporation | Datafiler | Microsoft Object Linking And Embedding Data | Microsoft Windows | Microsoft Corporation |
| .OSC | OpenStreetMap | GIS-filer | OpenStreetMap Change File | Microsoft Windows | Microsoft Corporation |
| .OSDX | Microsoft Corporation | Innstillingsfiler | Search Connector Description File | Microsoft Windows | Microsoft Corporation |
| .P5X | Microsoft Corporation | Systemfiler | Microsoft Windows System Data | Microsoft Windows | Microsoft Corporation |
| .P7B | Microsoft Corporation | Web-Filer | PKCS #7 Certificate File | Microsoft Windows | Microsoft Corporation |
| .P7C | Microsoft Corporation | Web-Filer | PKCS #7 Certificate File | Microsoft Windows | Microsoft Corporation |
| .PBK | Microsoft Corporation | Datafiler | Dial-Up Phone Book File | Microsoft Windows | Microsoft Corporation |
| .PBO | Bohemia Interactive | Spillfiler | Packed Bohemia Object | Microsoft Windows | Microsoft Corporation |
| .PCF | Blackstrip Studios | Fontfiler | PaintCAD Font | Microsoft Windows | Microsoft Corporation |
| .PCI | Microsoft Corporation | Systemfiler | PCI Miniport Data | Microsoft Windows | Microsoft Corporation |
| .PE | Microsoft Corporation | Eksekverbare filer | Portable Executable File | Microsoft Windows | Microsoft Corporation |
| .PIF | Microsoft Corporation | Eksekverbare filer | Program Information File | Microsoft Windows | Microsoft Corporation |
| .PMA | David Harris | Komprimerte filer | Pegasus Mail Data Archive File | Microsoft Windows | Microsoft Corporation |
| .PNF | Microsoft Corporation | Systemfiler | Precompiled INF File | Microsoft Windows | Microsoft Corporation |
| .POW | Microsoft Corporation | Innstillingsfiler | Microsoft Windows Power Schema | Microsoft Windows | Microsoft Corporation |
| .PPKG | Microsoft Corporation | Datafiler | Microsoft Windows Provisioning Package | Microsoft Windows | Microsoft Corporation |
| .PRF | Microsoft Corporation | Innstillingsfiler | Outlook Profile File | Microsoft Windows | Microsoft Corporation |
| .PRT | PTC | CAD-filer | Pro/ENGINEER Part File | Microsoft Windows | Microsoft Corporation |
| .PS2 | Datel | Spillfiler | Sharkport Saved Game File | Microsoft Windows | Microsoft Corporation |
| .PSSC | Microsoft Corporation | Systemfiler | Windows PowerShell Session Configuration File | Microsoft Windows | Microsoft Corporation |
| .PYS | Microsoft Corporation | Datafiler | Microsoft Console Based Script Host File | Microsoft Windows | Microsoft Corporation |
| .QDS | Microsoft Corporation | Uvanlige filer | Windows Directory Query File | Microsoft Windows | Microsoft Corporation |
| .RAT | World Wide Web Consortium (W3C) | Uvanlige filer | PICS Rating File | Microsoft Windows | Microsoft Corporation |
| .RESTORELIST | Microsoft Corporation | Systemfiler | Microsoft Windows File System Permission | Microsoft Windows | Microsoft Corporation |
| .RSP | Rockwell Automation Inc. | Datafiler | RSLogix PLC Program File | Microsoft Windows | Microsoft Corporation |
| .RX | Microsoft Corporation | Systemfiler | MS-DOS 7 Data | Microsoft Windows | Microsoft Corporation |
| .SCF | Microsoft Corporation | Systemfiler | Windows Explorer Command | Microsoft Windows | Microsoft Corporation |
| .SCR | Microsoft Corporation | Systemfiler | Windows Screensaver File | Microsoft Windows | Microsoft Corporation |
| .SCT | Scitex | Rasterbildefiler | Scitex Continuous Tone File | Microsoft Windows | Microsoft Corporation |
| .SEARCH-MS | Microsoft Corporation | Uvanlige filer | Windows Saved Search File | Microsoft Windows | Microsoft Corporation |
| .SEARCHCONNECTOR-MS | Microsoft Corporation | Datafiler | Microsoft Windows Search Connector Description File | Microsoft Windows | Microsoft Corporation |
| .SEC | Symantec Corporation | Uvanlige filer | Pretty Good Privacy Secret Key Ring | Microsoft Windows | Microsoft Corporation |
| .SF0 | Microsoft Corporation | Systemfiler | Windows Sytem File Check File | Microsoft Windows | Microsoft Corporation |
| .SFB | Sony | Spillfiler | PlayStation 3 Disc Data File | Microsoft Windows | Microsoft Corporation |
| .SFCACHE | Microsoft Corporation | Systemfiler | ReadyBoost Cache File | Microsoft Windows | Microsoft Corporation |
| .SHB | Microsoft Corporation | Eksekverbare filer | Windows Document Shortcut | Microsoft Windows | Microsoft Corporation |
| .SHD | Microsoft Corporation | Systemfiler | Windows Print Job Shadow File | Microsoft Windows | Microsoft Corporation |
| .SHS | Microsoft Corporation | Uvanlige filer | Microsoft Scrap File | Microsoft Windows | Microsoft Corporation |
| .SP1 | Microsoft Corporation | Datafiler | Microsoft Windows XP With Service Pack 1 Installation Data | Microsoft Windows | Microsoft Corporation |
| .SPL | Microsoft Corporation | Systemfiler | Windows Print Spool File | Microsoft Windows | Microsoft Corporation |
| .SQM | Microsoft Corporation | Systemfiler | Service Quality Monitoring File | Microsoft Windows | Microsoft Corporation |
| .STR | dBase, LLC | Datafiler | dBASE Structure List Object File | Microsoft Windows | Microsoft Corporation |
| .SWAP | Microsoft Corporation | Systemfiler | Swap File | Microsoft Windows | Microsoft Corporation |
| .SWP | Microsoft Corporation | Systemfiler | Swap File | Microsoft Windows | Microsoft Corporation |
| .SYS | Microsoft Corporation | Systemfiler | Windows System File | Microsoft Windows | Microsoft Corporation |
| .T2 | RM Education | Datafiler | Textease 2000 File | Microsoft Windows | Microsoft Corporation |
| .THEME | Microsoft Corporation | Systemfiler | Microsoft Plus! Desktop Theme | Microsoft Windows | Microsoft Corporation |
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