File formats and extensions
v2.0 r05jun2014

.---  Archived application distribution/installer information file (Same as DIZ extension).
.---  Backup file.
.---  Temporary file.
.~H   Temporary file (Antanas Zdramys' azzCardfile 4).
.~I   Temporary file (Antanas Zdramys' azzCardfile 4).
.!BT  Incomplete BitTorrent download (BitTorrent).
.###  Temporary file (Many applications).
.#$#  Temporary file (Ulead PhotoImpact 7).
.$$$  Auto-generated backup file.
.$$$  Temporary file (Sun's StarOffice suites).
.$$$  Temporary file (Ulead PhotoImpact 7).
.$$$  Used by OS/2 to keep track of archived files 
.$DB  Temporary dBase database file (Ashton Tate's dBase).
.@@@  Screen files used in the installation and instruction on use of such applications as Microsoft Codeview for C 
._    Unexpanded install file = file extension changed when expanded/installed.
._MP  Installshield Temporary file (Installshield Installer/Uninstaller packages).
.000 .999 Multi-volume archives or multi-volume backups (Many applications).
.0000 Package file in game software distributions (Ubisoft and others).
.001  Compressed volume file = a compressed archive that retains/maintains the content of a disk drive/volume or partition of a disk drive/volume (DoubleSpace).
.001  Cover page file (GFI Software Development's GFI FaxMaker).
.001  Fax cover page (Hayes JT Fax).
.001  Fax coversheet (SuperFax).
.001  SmartFax cover page file (SmartFax).
.001  SmartFax image file (Pierre-e Gougelet's XnView).
.0AF .FAF Aircraft texture file (Microsoft Flight Simulators, Martin Wright's BMP2000/BMP2K and other Extended Bitmap editors).
.1 .2 Disk snapshot image file (Ontrack Fix-It Utilities 3).
.1 .99 Game saves (Games/Applications, especially DOS-era).
.1 .999 Fax trace files (Brooktree faxboard hardware/software).
.123  Lotus 1-2-3 worksheet/spreadsheet (Lotus 1-2-3 v9/97).
.12M  Lotus 123 97 Smartmaster file 
.144  DOS 1.44MB floppy disk image file (QNX Installer).
.16   Files intended for use with, or by operators of computing devices with, 16-bit microprocessors, operating systems, and/or applications.
.1ST  Readme file = A text file whose content should be read before performing any task with it's accompanying files/data (Application or other file/data distributions).
.202  SR202 kit audio samples (Muon-Software SR202 VST plug-in).
.301  Brooktree 301 image file = the cover or first page of a fax transmission/series of pages (Pierre-e Gougelet's XnView).
.301 .399 Brooktree fax file (Brooktree fax hardware/software).
.32   Files intended for use with, or by operators of computing devices with, 32-bit microprocessors, operating systems, and/or applications.
.32B  32bit Fax station file (ElectraSoft 32bit Fax).
.386  Virtual device driver file (Microsoft Windows operating systems, many developers/applications).
.386  Windows swap or driver file (Win9x/3.x systems).
.3D   Draw3D version 2 format file (Draw3D).
.3D2  CAD 3D version 2 file (Tom Hudson's Atari computer CAD 3D program and many other programs).
.3DA  3D View Angle configuration file (WordPerfect Office x6).
.3DD  Jamagic 3D editor object file (Clickteam Jamagic).
.3DG  3D GIF Designer container file (PY Software's 3D GIF Designer).
.3DJ  Jamagic project file (Clickteam's Jamagic).
.3DMF 3D Meta File (Apple Quickdraw 3D and 3D editors/viewers).
.3DS  3D Studio binary format file (Draw3D).
.3DS  3D Studio mesh file (Autodesk 3DStudio Max and others).
.3DV  3D Canoma file (MetaCreations Canoma).
.3DW  3D World Studio file (Leadwerks 3D World Studio).
.3FX  3D Effects file (Corel Chart).
.3G2  3rd/Third Generation Partnership Project 2 movie = 3GPP2 (QuickTime, mobile phones, and many other applications).
Posted by Extensionarian at 7:37 AM No
.3GA  3GGP/Third Generation Partnership Project Audio file (Cellphones, VLCTeam's VideoLAN Client/VLC and other media playing applications/devices).
.3GP  3GPP movie (QuickTime, mobile phones).
.3GP2 3GPP2 movie (QuickTime, mobile phones).
.3GPP 3GPP movie (QuickTime, mobile phones).
.3MD  3D Model file (Corel Word Perfect Office).
.3PG  3D Photo Gallery project file (Etalon's 3D Digital Photo Gallery).
.3TF  3D Template File (Corel Word Perfect Office).
.404  TS-404 synthesizer sample file (Sonic Syndicate TS-404).
.4DP  4D Paint project file (4D Vision's 4D Paint).
.4TW  ToolWorks 4.x settings file (Pitrinec Software ToolWorks).
.602  602Text format document (602Software's 602Text).
.64   Files intended for use with, or by operators of computing devices with, 64-bit microprocessors, operating systems, and/or applications.
.669  669 format audio file (669 Tracker, Unis Composer music mod file, and many audio applications).
.7    7Zip archive file (Igor Pavlov's 7Zip File Manager and many other archiving applications).
.767  Temporary application installer file (Ontrack Fix-It Utilities 3).
.777  7Zip archive file (Igor Pavlov's 7Zip File Manager and many other archiving applications).
.7Z   7Zip archive file (Igor Pavlov's 7Zip File Manager and many other archiving applications).
.7ZIP 7Zip archive file (Igor Pavlov's 7Zip File Manager and many other archiving applications).
.850  FoxPro window font file (Microsoft FoxPro).
.852  FoxPro window font file (Microsoft FoxPro).
.8BA  Photoshop acquire module plug-in file (Adobe Photoshop).
.8BC  Photoshop plug-in file (Adobe Photoshop).
.8BE  Photoshop Export/Import plug-in file (Adobe Photoshop).
.8BF  Photoshop Filter/Effects plug-in file (Adobe Photoshop and many third party filter and effects developer software distributions).
.8BI  Photoshop Format plug-in file (Adobe Photoshop).
.8BIT 8-Bit newspaper/e-zine file.
.8BP  Photoshop plug-in file (Adobe Photoshop).
.8BS  Photoshop plug-in file (Adobe Photoshop).
.8BX  Photoshop Extension plug-in file (Adobe Photoshop).
.8BY  Photoshop Parser plug-in file (Adobe Photoshop).
.8LI  Photoshop Application plug-in file (Adobe Photoshop).
.906  Calcomp plotter file (Calcomp printer applications).
.A    ADA program file (ADA programming language).
.A    Addendum file (Documents/Texts).
.A    Archive file (KetilO's FbEdit FreeBASIC Editor).
.A    Archive file (Many applications).
.A    ASCII text document file (Many applications).
.A    Backup file.
.A00 .A99 Multi-volume ARJ archive file (Many applications).
.A11  AIIM monochrome/grayscale graphics file (Many image applications).
.A31  Macromedia Authorware 3 library file (Macromedia Authorware 3).
.A3D  Amapi 3D model project file (Amapi 3D).
.A3K  A3000 digital audio sample file (Yamaha A3000).
.A3L  Macromedia Authorware 3 Library file (Macromedia Authorware 3).
.A3M  Macromedia Authorware 3 for Macintosh file (Macromedia Authorware 3 Macintosh operating system).
.A3W  Macromedia Authorware 3 for Windows file (Macromedia Authorware 3 for Windows operating system).
.A41  Macromedia Authorware 4 Library file (Macromedia Authorware 4).
.A4L  Macromedia Authorware 4 Library file (Macromedia Authorware 4).
.A4M  Macromedia Authorware 4 Module for Macintosh file (Macromedia Authorware 4 Macintosh operating system).
.A4P  Macromedia Authorware 4 Program file(Macromedia Authorware 4).
.A4W  Macromedia Authorware 4 Module for Windows file (Macromedia Authorware 4 Windows operating system).
.A51  Macromedia Authorware 5 Library file (Macromedia Authorware 5).
.A5L  Macromedia Authorware 5 Library file (Macromedia Authorware 5).
.A64  Artist 64 image format file.
.A64  Commodore 64 SID audio file (SIDplay32).
.A6D  Authorware 6 model file (Macromedia Authorware 6).
.A6E  Authorware 6 External library file (Macromedia Authorware 6).
.A6L  Authorware 6 Library file (Macromedia Authorware 6).
.A6P  Authorware 6 Project file (Macromedia Authorware 6).
.A6R  Authorware 6 Runtime file (Macromedia Authorware 6).
.A8   24bit 3D animation file (Cubicomp PictureMaker).
.A86  Intel x86 Assembler source code file.
.A98  AGFA ProSet 9800 printer support file.
.AA   ASCII or ANSI Art file. Drawings or animation composed entirely of text. ANSI requires ANSI-capable reader or device/hardware (Terminal programs, e-readers, etc).
.AA   Audio book file.
.AA   Automated Analyst document file (PROGNOSIS Automated Analyst).
.AAA  AppCam Automation file (AppCam).
.AAA  Backup file.
.AAA  Softphrase Automation file.
.AAA  Temporary file.
.AAB  Authorware Binary file (Macromedia Authorware).
.AAC  AAC audio file (Media players and other audio applications).
.AAC  Advanced Audio Coding format audio file (Many applications).
.AAC  Advanced Audio Coding format audio stream file (many applications).
.AAM  Authorware Map file (Macromedia Authorware).
.AAO  America's Army game map Overview file (America's Army).
.AAP  Apollo Advanced playlist file.
.AAS  Authorware Segment file (Macromedia Authorware).
.AB   Applix Builder data file (Applix Builder).
.AB$  AutoCAD plot file (Autodesk's AutoCAD).
.AB2  Address Book file (Parson's Address Book 2).
.AB3  Album file V3 file (Ulead PhotoImpact 3 Album).
.AB6  AB Stat 6 data file.
.AB8  AB Stat 8 data file.
.ABA  Address Book file (Palm operating system applications and Palm OS emulators).
.ABC  ABC Flowcharter image file (ABC Flowcharter).
.ABC  Musical Notation language file.
.ABC  PageABC Web Document/Template file = HTML markup (Bridgewell/ABCHood.com PageABC).
.ABE  ABE control file (Mozilla Firefox).
.ABF  Adobe Binary screen Font file (Adobe Systems' applications).
.ABI  ARM binary/executable file (Android cellphones and other ARM microprocessor driven devices).
.ABICOLLAB AbiWord Collaboration document file (AbiSource AbiWord).
.ABK  Address Book database 1.0 file (MindScape PrintMaster Gold).
.ABK  Address Book database file (MindScape PrintMaster).
.ABK  Automated Backup file (Many applications).
.ABKBAK Ashampoo Backup file (Ashampoo's Burning Studio).
.ABKPRJ Ashampoo Backup Project file (Ashampoo Burning Studio).
.ABM  Album file (Many applications).
.ABM  Album file (Ulead PhotoImpact Album).
.ABO  Applix Builder file (Applix Builder).
.ABR  Adobe Photoshop Brushes file (Adobe Photoshop and other image editors).
.ABS  Abstract file.
.ABW  Uncompressed AbiWord format document file (AbiSource AbiWord). ABW.GZ=GZip compressed, .ZABW=ZIP compressed.
.ABX  Address Book file (Corel WordPerfect 8).
.AC$  AutoCAD temporary/undo file (Autodesk AutoCAD).
.AC3  AC3 audio format file = A/52 audio format file (Many media applications).
.AC3  Dolby Digital AC3 format audio file (many applications).
.ACA  Microsoft Agent character file (Microsoft Windows).
.ACA  Project Manager workbench file in HTTP format (Microsoft Windows).
.ACB  ACBM Bitmap image file (Image editors).
.ACB  Application/installer Cabinet file (America Online CDs).
.ACC  Viewmax file (Dr-DOS).
.ACCDB Access Database file (Microsoft Access 2007 and other database applications).
.ACCESS Java Runtime Environment (JRE) Remote JMX API access control file (Plaintext).
.ACCESS Remote Access control file - contains name and pass of administrator (VideoLAN Team's VideoLAN Client/VLC).
.ACD  ACDSee file (ACD Systems' ACDSee).
.ACD  Acid music data file (Sonic Foundry Acid).
.ACD  allCLEAR Drawing file (allCLEAR).
.ACD  allCLEAR Flowcharting Data file (allCLEAR).
.ACD  Channel Data file (Chromeleon).
.ACD  Agent Character Definiton data file (Microsoft Windows Agent).
.ACE  ACE DXT1 texture file (Martin Wright's DXTBmp Editor).
.ACE  ACE format archive container file (Marcel Lemke's WinACE and other archiving applications).
.ACE  Aces200 image file (Many image applications).
.ACF  Adobe Photoshop Custom Filter file (Adobe Photoshop).
.ACF  Advice Calculator database file (BM Software Advice Calculator).
.ACF  Agent Character File in HTTP format (Microsoft Agent).
.ACF  Application configuration file (TMPGEnc MPEG video encoder).
.ACG  Agent Graphics preview file (Microsoft Windows Agent).
.ACH  System snapshot file (Speccy).
.ACL  AutoCorrection List file (Microsoft Office).
.ACM  ACBM bitmap image file.
.ACM  Audio Compression Manager codec file (Microsoft Windows).
.ACM  Compressed audio file (Interplay).
.ACO  Adobe Color swatches file (Adobe Photoshop/Photo Elements).
.ACO  ArtWeaver Color set file (Boris Eyrich Software Artweaver).
.ACR  American College of Radiology image format file (Many image applications).
.ACR  Dicom image file (Many image applications).
.ACRODATA Acrobat user Data store file (Adobe Acrobat).
.ACS  Microsoft Agent Character file (Microsoft Windows).
.ACS2 Skin package v2 file (AIMP media player).
.ACS3 Skin package v3 file (AIMP media player).
.ACSRF Audition Control Surface plug-in file (Adobe Systems' Audition).
.ACT  Access Codes for font file (Microsoft Windows).
.ACT  Adobe Color Table/palette file (Adobe Systems' Photoshop and other image editors).
.ACV  Adobe Photoshop Curves file (Adobe Photoshop).
.ACW  Accessibility Wizard configuration file (Microsoft Windows).
.ACX  File description file (FOCUS/WebFOCUS).
.AD   Advertisement file = JPEG or GIF image.
.AD   Ascend password protocol file (Ascend).
.AD   Screensaver application file (Berkeley Systems After Dark Deluxe 4).
.ADA  ActiveDocs Answer set file.
.ADA  ADA program file (ADA programming language).
.ADA  Adaptation file (eMagic SoundDiver).
.ADB  Account Database file (CIX's Ameol2).
.ADB  ADA package Body file (ADA programming language).
.ADB  ADA programming language batch file (Many applications).
.ADB  Address Book file (Corel's Word Perfect Office).
.ADB  AddWeb Database file (CyberspaceHQ's Addweb).
.ADB  Appointment Database file (HP Organizers).
.ADC  Analog to Digital Conversion speech control file.
.ADC  Demo Container file (Chromeleon).
.ADCF Audio Dedupe Cache File (MindGems' Audio Dedupe).
.ADD  Address file (Adobe Systems' Pagemaker).
.ADD  Advantage Database Server Dictionary file.
.ADD  OS/2 adapter drivers used in the boot process
.ADDON Addon configuration file (WinZIP).
.ADE  Access Database project Extension file (Microsoft Access 2002).
.ADF  Amiga Disk Format disk image file (Commodore Amiga operating system).
.ADF  Amiga Disk Format image file (Amiga Forever Amiga operating system emulator).
.ADF  Auction Designer workspace data File (Auction Designer 3).
.APD  Aml Pages documents List file (Mazov Gosha's Aml Pages notes manager).
.ADM  Administrative policy template file (Microsoft Windows).
.ADM  After Dark screensaver Module file (After Dark).
.ADN  Access New/blank Document template file (Microsoft Access 2002).
.ADN  Add-in file (Lotus 1-2-3).
.ADN  Add-on file (CIX's Ameol2).
.ADO  Adobe Duotone Options file (Adobe Photoshop).
.ADP  Access Database Project file (Microsoft Access).
.ADP  AOLserver Dynamic Page file (America OnLine).
.ADPF Audio Dedupe Project File (MindGems' Audio Dedupe).
.ADR  Address Book file (Many applications).
.ADR  Address book file (Smart Address).
.ADR  Address Plus Database file (AddressPlus).
.ADR  Addresses/bookmarks file (Opera web browser).
.ADR  After Dark Random screensaver module file.
.ADR  AntiDupl saved Results file (Yermalayeu Ihar AntiDupl.NET).
.ADS  ADA package Specification file.
.ADS  ADA programming language script file (Many applications).
.ADSITES Ad/Adserver database file (Deerfield Communications' InterQuick Voyager).
.ADT  AdTech fax file (AdTech Fax).
.ADT  Auction Designer Template file (Auction Designer 3).
.ADT  Check drawing integrity Diagnostic Tool report file = ASCII text (CorelCAD).
.ADT  Database file (Advantage Data Server).
.ADT  Dictionary file (Lingo).
.ADT  HP NewWave Card Application Data file.
.ADTS ADTS audio file (QuickTime Player 7.7.2).
.ADV  Adventure data file.
.ADV  Audio Driver file for sound cards (DOS/MS-DOS games).
.ADV  GUS virtual device Driver file.
.ADX  Archetype Designer document file (Archetype Designer).
.ADX  Dynazip Active Delivery script file.
.ADX  Index file (Lotus' Approach).
.ADZ  GZ compressed Amiga Disk file (Amiga Forever and other Amiga operating system emulators).
.AE   Author/Editor file (SoftQuad's HoT MeTaL Pro).
.AEDLAYOUT Auto-Run Editor Layout file (Ashampoo Burning Studio 11).
.AEDTHEME Auto-Run Editor Theme file (Ashampoo Burning Studio 11).
.AEP  After Effects Project file (Adobe After Effects).
.AEP  ArcExplorer Project file (ArcExplorer).
.AEPX After Effects Project XML file (Adobe After Effects).
.AES  After Effects Stabilizer settings file (Adobe After Effects).
.AET  After Effects Transfer settings file (Adobe After Effects).
.AEU  Europe Route file (Microsoft's AutoRoute Express).
.AEX  Adobe Extra transfer modes plug-in file (Adobe Systems' After Effects).
.AEX  Armored Extracted Public Encryption Key file (Pretty Good Privacy).
.AF2  ABC Flowchart v2 file (ABC FlowChart).
.AF3  ABC Flowchart v3 file (ABC FlowChart).
.AFC  Apple Format Compressed audio file (Audio applications).
.AFC  ArisFlow Commander file (ArisFlow).
.AFD  ActiveFile Data file (Prismo Graphics ActiveFile).
.AFD  After Dark file (After Dark screensaver application).
.AFD  ArisFlow Diagram file (ArisFlow).
.AFF  Affixes, prefixes, suffixes file (many applications).
.AFF  AnyForm Form file (AnyForm).
.AFFIX Affixes file (AbiSource's AbiWord).
.AFI  Truevision bitmap graphic image file (Image editors).
.AFL  Lotus Font file (Lotus 1-2-3).
.AFM  Adobe Font Metrics file for Adobe type font files (many applications).
.AFM  Cardfile Application file (HP NewWave).
.AFP  ActiveFile Proxy file (Prismo Graphics ActiveFile).
.AFP  Ameol File transfer Protocol application (CIX's Ameol2).
.AFP  Flowchart symbol Palette file.
.AFS  Audio File (Sega systems).
.AFT  ABC Flowchart Template file (ABC Flowchart).
.AFT  AnyForm Template file (AnyForm).
.AFT  Audio Filter plug-in library file (Ulead Systems MediaStudio 5).
.AFW  ABC Flowchart Work Area file (ABC Flowchart).
.AG   Applix Graphic image file.
.AG   Argus spreadsheet file.
.AG4  Access G4 file.
.AGF  Atlas GeoFile format file.
.AGP  Video driver documentation for AGP video card.
.AHF  ASP document Header File.
.AHK  Auto Hotkey hotstrings file (Bartels Media PhraseExpress).
.AHN  Ahnenblatt database file (Ahnenblatt geneaology program).
.AHN  Ahnenblatt family tree file (Ahnenblatt geneaology program).
.AHQ  AudioHQ plug-in file (Creative soundcard EAX effects control).
.AHS  Adobe Photoshop Half-tone Screens file (Adobe Photoshop).
.AHU  Adobe Photoshop Hue and Saturation adjustment/settings file (Adobe Systems Photoshop).
.AHY  AutoHotKey file.
.AI   Adobe Illustrator vector drawing file. A number of different variants all native to that program. Some third party graphics applications support it (Adobe Illustrator).
.AI   After Image file (Progress Database).
.AI   Corel Trace drawing file = Adobe Illustrator format (Corel's CorelDRAW).
.AIF  Application Information File (Symbian operating systems).
.AIF  Audio Interchange File Format/AIFF uncompressed audio file (Apple QuickTime).
.AIFC Audio Interchange File Format Compressed audio file (QuickTime 7.7.2).
.AIFF Audio Interchange File Format uncompressed audio file (Apple QuickTime).
.AIFF Macintosh AIFF uncompressed audio file (Many applications).
.AIJ  After-Image Journal file.
.AIM  AOL Instant Messenger shortcut file (America OnLine/AOL Instant Messenger).
.AIML Artificial Intelligence Markup Language file (Plaintext markup).
.AIMPPL AIMP3 Playlist file (AIMP Player 3).
.AIN  AIN compressed archive file.
.AIO  APL Input/Output format file.
.AIR  Air installer package file (Application distributions installed with Adobe Air).
.AIS  Album/Image Sequence file (ACD Systems' ACDSee).
.AIS  Array of Intensity Samples format image file (Image editor/viewer applications).
.AIX  AIX Unix documentation file for applications designed for multiple operating systems.
.AIX  Cardfile Application data file (HP NewWave).
.AKB  Assistum Knowledge Base file (Assistum).
.AKF  Acrobat Key File (Adobe Acrobat).
.AKS  ArtWeaver Keyboard Shortcuts file (Boris Eyrich Software Artweaver).
.ALB  Album file (Jasc Media Center Plus).
.ALB  Album/playlist file (Carlanthano Player = Radiate-infested adware).
.ALB  Backup file (Steinberg Cubase).
.ALB  JASC Image Commander Album (JASC Image Commander).
.ALB  Photo album/thumbnail set file.
.ALB  Web project Album file (ixla Web Easy).
.ALBM Photo Album file (webAlbum).
.ALBM Photo printing Album file (HP Photosmart).
.ALD  DVD Album project file (Anix' DVD Album).
.ALE  Advanced Landscape Editor project file (Dyvision Works' Advanced Landscape Editor).
.ALE  Avid Log Exchange file.
.ALF  ACT! file.
.ALIAS Alias Image (many image applications).
.ALL  Documentation/text file = For all users/operating systems.
.ALN  Align project file (Visual Computing Lab - ISTI - CNR's MeshLab).
.ALS  Alias image file (many image applications).
.ALT  ALT file (WordPerfect Corporation WordPerfect).
.ALV  Adobe Photoshop Levels file (Adobe Photoshop).
.ALV  Vbox Available Languages file (Aladdin Knowledge Systems software distribution).
.AM   Amplitude Modulation monophonic audio file.
.AM   Applix Macro file (Applix Shelf).
.AM2  AutoPlay Menu Studio 2 file (Indigo Rose's AutoPlay Menu Studio).
.AM3  AutoPlay Menu Studio 3 file (Indigo Rose's AutoPlay Menu Studio).
.AM4  AutoPlay Media Studio 4 file (Indigo Rose's AutoPlay Media Studio).
.AMB  Radiance Ambient format file.
.AMC  AMC movie file (QuickTime 7.7.2).
.AMC  Ant Movie Catalog file (Ant Movie Catalog).
.AMF  Additive Manufacturing File Format file = XML-based.
.AMF  Advanced Module Format audio file.
.AMH  AudioMulch document file (Ross Bencina's AudioMulch).
.AMI  AmiDiag file.
.AMI  Amiga Paint image file (many image applications).
.AMIO Amio Plug-in file (Adobe Systems' Audition).
.AML  AutoMage file.
.AML  Automate Markup Language file.
.AMP  Adobe Photoshop Arbitrary Map settings file (Adobe Photoshop).
.AMR  Adaptive Multi-Rate audio file (QuickTime 7.7.2).
.AMS  Adobe Photoshop Monitor Setup file (Adobe Photoshop).
.AMS  AudioMulch Set file (Ross Bencina's AudioMulch).
.AMS  Extreme's Tracker Module file.
.AMSF Auto-Run Maker Saved Files file (Abhishek's Auto-Run Maker).
.AMZ  Game save file (The Amazon Trail).
.AN8  Anim8or 3D animation file (Anim8or).
.ANI  Animated cursor file (Microsoft Windows, Impact's Microangelo and other image applications).
.ANIMATION Animation project file (Insane Tools' 3D Flash Animator 3).
.ANL  Analysis file (Project Analyzer).
.ANM  Animation image file (DeluxePaint Animator).
.ANM  Jamagic animation file (Clickteam Jamagic).
.ANN  Annotation file (Windows operating system Help system/HELP.EXE).
.ANO  Annotation file.
.ANS  ANSI image file.
.ANT  SimAnt game save file (Maxis/Imagineer's SimAnt).
.ANV  AirNav file (many image applications).
.AOB  DVD audio file (MPEG-2 program streams with additional info).
.AOF  Acorn Object Format file.
.AOI  Art Of Illusions file (Peter Eastman's Art Of Illusions).
.AOM  After Effects Output settings file (Adobe After Effects).
.AOS  Add-on/plug-in file.
.AP   Application file.
.AP   Application information file (driver installers - SiS, Cmedia, etc).
.AP   WHAP archive file (Amiga operating system and emulators).
.APA  AlfaPad file (AlfaAlfa Software AlfaPad).
.APA  Applet file (ArcPad).
.APC  Assistum Project Case scenario file (Assistum).
.APD  Aml Pages Document file (Mazov Gosha's Aml Pages notes manager).
.APE  Monkey Audio APE lossless audio format file (Many applications).
.APF  Acrobat Profile file (Adobe Acrobat).
.APF  Animator Project File (SanoLogic gr44 Animator).
.APF  Profile file (ArcPad).
.APF  Project File (Homesite).
.API  Adobe Photoshop Printing Inks color configuration file (Adobe Photoshop).
.API  Aml Pages Import file (Mazov Gosha's Aml Pages notes manager).
.API  Application Plug-In file (KetilO's FbEdit FreeBASIC Editor).
.API  Application Program Interface/driver file (many applications).
.APIN APIN plug-in file (Adobe InDesign).
.APJ  ARM Project file (ARM Project Manager).
.APK  Ad Packed file = packed graphic image (UltraPlayer).
.APK  Archive. PK=PK ZIP. The extension is used in cellphones and other usually portable devices.
.APL  ACDSee32 Plug-in file (ACD Systems' ACDSee v3.1).
.APL  Adobe Photoshop Plug-in file (Adobe Photoshop and many other image editors).
.APL  APL workspace file.
.APL  APlus Encrypted folder file (A+ Folder Locker).
.APL  ArcPad Layer file (ArcPad).
.APL  Plug-in file (AceHTML).
.APM  ArcPad file (ArcPad).
.APO  Apollo script file.
.APP  Application file (Clarion).
.APP  Application file (Many operating systems, programs, and many variants).
.APP  Application object file (Ashton Tate dBASE).
.APP  ArcPad Project file (ArcPad).
.APPCACHE Appcache manifest file.
.APPLICATION Application deployment manifest file (Microsoft Windows).
.APPREF-MS Application deployment reference file (Microsoft Windows).
.APR  Approach data file (Lotus Approach 97).
.APS  Assistum Project Space file (Assistum).
.APS  Microsoft Visual C++ file.
.APS  Symbology file (ArcPad).
.APT  Approach Data View file (Lotus Approach 97).
.APT  Alphacam Punch Tool/APT file (IGESToolbox).
.APTHME Aml Pages Theme file (Mazov Gosha's Aml Pages notes manager).
.APX  Ability Photopaint image file (Ability Photopaint).
.APX  Appexpert file (Borland Appexpert).
.APX  Approach file (Lotus Approach 97).
.APX  ArcPad XML file (ArcPad).
.AR   Archive/Archive distribution file (Many games and applications, many variants).
.ARA  ATI Radeon driver file (ATI video cards).
.ARC  ARC format archive container file (Many OSs and variants).
.ARC  Archimedes drawing file = XML markup (Tarantulus' Archimedes the Open CAD).
.ARCHIMEDES Snapshot file (Speccy).
.ARG  ArrangeNote file (KYamamoto's ArrangeNote).
.ARJ  ARJ format archive container file (Many archiving applications).
.ARK  ARK format archive container file.
.ARN  Astronomical Research Network file (many image applications).
.ARN  Autoruns saved registry scan results file (SysInternals' Autoruns).
.ARPX8 Arp-X8 MIDI arpeggiator file.
.ARQ  Archive file.
.ARR  Arrangement file (Audio applications).
.ARS  After Effects Render Settings file (Adobe After Effects).
.ART  America Online ART file (Many image editors and viewers).
.ART  Another Ray Tracer format image file (Many image editors and viewers).
.ART  Art Director image file (Art Director).
.ART  Artisan file.
.ART  Canon Crayola Art file.
.ART  Clip Art file (many image applications).
.ART  Drawing file (Xara Studio).
.ART  PFS: Art Publisher file (many image applications).
.ARV  Arsiv file.
.ARV  AutoRoute User Information file.
.ARW  Sony DSLR RAW format image file (Many variants).
.ARW  Sony RAW format image file (Sony cameras, many image applications, many variants).
.AS   Action Script file (Macromedia/Adobe Flash development and web developer applications).
.AS   Apple Single format archive container file (Smith Micro's Stuffit and other archive applications).
.AS   Applix Spreadsheet file.
.AS4  AS/400 client access file.
.ASA  Active Server document file (August Wind's ASP Express).
.ASC  3D Studio ASCII format file (Draw3D).
.ASC  ActionScript source code file (Text highlighting text editors and web developer applications).
.ASC  ASCII text file (Many applications).
.ASC  Assembler Source Code file.
.ASD  Advanced Streaming Format Description file = Accompanies Microsoft ASF video/audio files or directs applications to Microsoft ASF content (Many applications).
.ASD  ASF Descriptor file (Microsoft Windows Media Encoder).
.ASD  Astound Presentation file.
.ASD  Auto-Saved Document file (Microsoft Word).
.ASD  Screen Driver file.
.ASDB Archive System Database file = Media catalog (Sayyid Mohammad Saleh Samimi's Archive System 1.9).
.ASES Audition Session Plug-in file (Adobe Systems' Audition).
.ASF  Active Streaming Format file (A proprietary Microsoft streaming media container format).
.ASF  Lotus Screen Font file.
.ASF  Statgraphics data file.
.ASH  ArtWeaver custom Shape file (Boris Eyrich's ArtWeaver).
.ASH  ArtWeaver Shape file (Boris Eyrich Software Artweaver).
.ASH  Assembler Header file (TASM assembler).
.ASHDISC AShampoo Disc image file (Power Software's Free Any Burn).
.ASHLANG Ashampoo Language localization file (Ashampoo's Burning Studio).
.ASI  Assembler Includes file (Borland Assembler).
.ASK  askSam database file.
.ASM  Assembly language source code file (Virtually all systems/OSs and their assembly/disassembly applications that have assembly programming facilities use this extension).
.ASM  Generic Assembler source code file (Digia Qt Creator).
.ASMX ASP.NET Webservices source file.
.ASN  Assistum Scenario file (Assistum).
.ASO  Assembler Object file.
.ASP  Active Server Page/Document file (Servers, browsers, web developer environments).
.ASP  Adobe Photoshop color Separation setup file (Adobe Photoshop).
.ASP  ASPECT program file (Procomm Plus).
.ASPX ASP.NET source file.
.ASR  Microsoft Automap route file.
.ASRC ARM microprocessor Assembly Source code file.
.ASS  Advanced Substation Alpha format sub-titles file (Aegisub).
.ASS  Assembly language source code file (Many applications).
.AST  Adobe Photoshop color Separation Table file (Adobe Photoshop).
.AST  Assistant file (Claris Works' Assistant).
.AST  Assistant file (Corel Office X6 PerfectExpert Assistant).
.AST  Astound! media file (Astound!).
.ASV  Adobe Photoshop Selective color adjustments file (Adobe Photoshop).
.ASV  Auto-Saved document/project file (QuarkXPress).
.ASV  Auto-Saved file (DataCAD).
.ASX  Advanced Streaming Redirector file = Microsoft's playlist format for MediaPlayer. Unfortunately, some applications use this extension to store video and/or audio, so manual content determination is often required.
.ASX  Cheyenne Backup script file.
.AT2  Auto Template file (Aldus Persuation 2).
.ATF  Adobe Photoshop Transfer Functions file (Adobe Photoshop).
.ATK  Andrew Toolkit bitmap image file (Andrew Toolkit).
.ATM  Adobe Type Manager database file (Adobe Systems' Type Manager).
.ATN  Actions file (Adobe graphics/image applications).
.ATP  Accel spreadsheet/worksheet Template file (SSuite Office Accel).
.ATR  Material library file (Lightscape).
.ATT  AT&T Group 4 bitmap format image file = the standard fax image format (Many fax devices/applications and image applications).
.ATU  aTunes playlist file (aTunes Team aTunes).
.AU   Linear or µ-law/Mu-Law compressed audio file (QuickTime and many other audio applications).
.AU3  AutoIt version 3 script (Image and Text editors).
.AUCTIONFERRETSEARCH AuctionFerret saved Search file (AuctionFerret).
.AUD  Audio file (many applications).
.AUP  Audacity native Project file (Audacity Team's Audacity).
.AUR  Aura project file (Hervé Adam's Aura).
.AUT  Authentication/verification file (Many applications).
.AUT  Auto-Illustrator file.
.AUT  AutoIt script file (AutoIt).
.AUTHEDTHEME Authoring Editor Theme file (Ashampoo Burning Studio 11).
.AUX  Auxilliary dictionary file (ChiWriter).
.AVA  Adobe Photoshop Variations file (Adobe Photoshop).
.AVA  Avagio file.
.AVASTCONFIG Avast configuration file (Avast Virus).
.AVASTLIC Avast License file (Avast Virus).
.AVASTSOUNDS Avast! Sound package file (Avast! Antivirus).
.AVASTTHEME Theme file (Avast Virus).
.AVB  Character file (Microsoft Chat).
.AVC  Kaspersky Antivirus Toolkit file.
.AVD  Avery Data file (Avery Label Pro).
.AVE  Avenue file (ActiveState's Komodo Edit).
.AVI  Microsoft Audio Video Interleave file (QuickTime 7.7.2 and many other video applications).
.AVL  AV List slideshow file (AV List).
.AVP  Avid Project file.
.AVPRESET Audio/Video project configuration file (Dominique Levray's ffDiaporama).
.AVR  AV Research audio file (Audio applications).
.AVS  Advanced Visualization Studio plug-in file (Nullsoft WinAmp).
.AVS  Animation project file.
.AVS  Avisynth File (scripting language and filters for non-linear video editing).
.AVS  Stardent AVS X Image file (image applications).
.AVSI AviSynth file.
.AW   AdvanceWrite Text file (HP AdvanceWrite).
.AW   Answer Wizard file = a file supporting the Answer Wizard help querying system found in Microsoft applications (Microsoft Windows, Microsoft Office and other Microsoft application suites).
.AW   Applix Words document file (Applix Words).
.AWB  Ad-Aware Backup file (LavaSoft AdAware).
.AWC  Another World Creator file (Juan Ignacio Odriozola's Another World Creator).
.AWD  ArtWeaver Document file (Boris Eyrich Software Artweaver).
.AWD  Award BIOS logo file.
.AWD  Fax file (Microsoft Fax).
.AWE  ArtWeaver Events file (Boris Eyrich Software Artweaver).
.AWK  AWK programming language script/program file (Unix/Linux' AWK utility and AWK utilities in other operating systems).
.AWL  AudioWriter Layout file (R.M. de Boer Software's AudioWriter).
.AWM  AnimationWorks Movie file.
.AWR  Ad-Aware file (LavaSoft Ad-Aware).
.AWT  AbiWord document Template file (AbiSource AbiWord).
.AWTEAM ArtWeaver Team file (Boris Eyrich Software Artweaver).
.AX   DirectX/DirectShow filter file (Microsoft Windows operating system).
.AXE  Autoroute Export file (Microsoft Autoroute).
.AXP  CDBurnerXP file (Canneverbe CDBurnerXP 4).
.AXT  Adobe Photoshop color replacement file (Adobe Photoshop).
.AY   AY soundchip file (Game/OS emulators).
.AZ   WinDVD file.
.AZZ  AZZ AvCardfile Personal Information Manager file.
.AZZ  Compressed AZZ cardfile (Antanas Zdramys' azzCardfile 4).
.AZZX Uncompressed AZZ cardfile (Antanas Zdramys' azzCardfile 4).
.B    Backup file.
.B    Batch file.
.B&W  Black and White or Mono color image file.
.B_W  Black and White or Mono color image file.
.B3D  Blitz3D mesh prop file (Dyvision Works' Advanced Landscape Editor).
.B3D  Blitz3D model or mesh file (Blitz3D and many BlitzBasic applications).
.B4   Backup file.
.B5I  BlindWrite 5 disk Image file (VSO Software's BlindWrite 5, Power Software's Free Any Burn).
.B5T  BlindWrite 5 disk image Table of contents file (VSO Software BlindWrite 5).
.B64  Base 64 encoded file - MIME encoded (Many applications).
.B6T  BlindWrite 6 disk image Table of contents file (VSO Software's BlindWrite 6).
.BA_  Sample Batch file (ZedTech's ZTreeWin).
.BA1  Backup file (Integra Computing's BillPower).
.BAC  Bacchus game save file.
.BAC  Backup file.
.BACK Backup file.
.BACKUP Automatic Backup file (Matt Pyne's TinyCAD).
.BACKUP Backup file.
.BAD  Bad/damaged file.
.BAFL BurnAware File List file (BurnAware Technologies' BurnAware).
.BAK  Backup file (Many applications).
.BAL  Ballade musical score file (Many audio applications).
.BAM  Block Availability Map file.
.BAN  Babarosa GIF Animation project file (Liatro's Babarosa).
.BAN  Banner document file (Sierra On-Line's Print Artist 3).
.BAN  Banner project file (MindScape PrintMaster).
.BANM Bannermaker banner file (Bannermaker).
.BAS  Beginners All purpose Symbolic Instruction Code/BASIC module or subroutine file (many BASIC programming language variants).
.BAS  Beginners All purpose Symbolic Instruction Code/BASIC program file (many BASIC programming language variants).
.BAS  Beginners All purpose Symbolic Instruction Code/BASIC program code snippet file (many BASIC programming language variants).
.BAS  Beginners All purpose Symbolic Instruction Code/BASIC program source code file (many BASIC programming language variants).
.BAS  FreeBASIC program or source code file = text (FreeBasic IDE, KetilO's FbEdit FreeBASIC Editor, Nicholas Christopoulos' SmallBASIC and many other applications).
.BAT  Batch file = a script file that supports branching and logical functions that executes command line arguments similar to Unix shell scripts (DOS/Windows operating systems).
.BATCH Batch file.
.BAU  Archive format container (Lotus Symphony).
.BAU  Writer Autotext resource file locations (LibreOffice).
.BB   Blitz Basic language program or script file (Dyvision Works' Advanced Landscape Editor).
.BB   Blitz Basic source code or application (Blitz Basic, Komodo Edit, and other applications).
.BB2  Archiver control file (ZedTech's ZTreeWin).
.BBC  BBC BASIC program file.
.BBC  BBCode file.
.BBL  Benchmark Baseline file = user generated results file (Dacris Benchmark).
.BBL  Bibliography file.
.BBL  TeX Bibliography file.
.BBM  Bitmap image file (Deluxe Paint).
.BBS  Bulletin Board System file or documentation (Many BBS/bulletin board applications).
.BC   Business Card document file (Sierra On-Line's Print Artist 3).
.BCH  Batch file.
.BCKIT Beatcraft Kit file (Acoustica's Beatcraft).
.BCP  Bitcollider Plug-in container = ZIP archive (Bitzi's BitCollider).
.BCP  Borland C++ file.
.BCP  Business Card file (CAM Development Business Card Designer Plus).
.BCPROJ Beatcraft Project file (Acoustica's Beatcraft).
.BCSAMPLE Beatcraft Sample file (Acoustica's Beatcraft).
.BCTEMPLATE Beatcraft project Template file (Acoustica's Beatcraft).
.BD   Boulder Dash game levels container file.
.BDB  Burner Database file (NewTech/Creative SoundBlaster cards).
.BDF  NuGraf Scenes file (Okino Computer Graphics' PolyTrans).
.BDMV BluRay Disc Movie file (BD media).
.BDR  Borders file = Document border decoration bitmap images and reference indexes for Office applications (Microsoft Office).
.BER  Boss Everywhere Report file (Alexander Jmerik's Boss Everywhere 2).
.BEV  Button bevelling template file.
.BEVEL Bevel file (Neuber Font Twister).
.BF   Blowfish encrypted file (Document encryption/decryption applications).
.BFC  Briefcase file = Container/archive file (Microsoft Windows operating systems).
.BFC  Font configuration file (IBM Lotus Symphony).
.BFC  Font configuration file (Sun/Oracle Java Runtime Environment/JRE).
.BFF  Buttonz! Factory File (Buttonz!).
.BFT  Bitmap Font Table image file = bitmap image (Font manager applications).
.BFX  BitFax Fax file (Bitware BitFax).
.BG   Background image tile/texture file (Games).
.BGI  Borland Graphics Interface file = Video card driver for a Borland C++ application.
.BGL  Background scenery Library file (Microsoft Flight Simulator - many variants).
.BGT  Budget database file (William Odlum's Budget For Success).
.BHO  Browser Helper Object file = GIF static image (Nothing Else Matters' vTuner).
.BHX  BinHex format archive container (Many applications).
.BI   FreeBASIC include/headers file (KetilO's FbEdit FreeBASIC Editor, FreeBasic IDE).
.BIB  Bibliography document file.
.BIB  BibTeX document file.
.BIBTEX BibTeX document file.
.BIF  Boot Image File (Power Software's Free Any Burn).
.BIF  byLight 20/20 Image File (byLight Technologies' 20/20 2.2).
.BIK  Bink encoded video file frequently employed by game developers (Bink).
.BIN  Compressed volume file (DoubleSpace).
.BIN  Binary data file (Too Many OSs and applications).
.BIN  MacBinary archive file (SmithMicro's Stuffit Deluxe and other archive applications).
.BIN  Raw binary disk/RAM/ROM image (Many applications, many variants).
.BINK Bink encoded video file frequently employed by game developers (Bink).
.BIT  Bitmap image file = Microsoft Windows BMP image (Many applications).
.BITMAP Bitmap image project file (Insane Tools' 3D Flash Animator 3).
.BIZ  Business card project file (MindScape PrintMaster Publishing Suite).
.BIZ  Business/developer's contact/ordering information file.
.BJC  Documentation for BJC series printers.
.BK6  SafeIT address book Backup file (SoftNet Security's SafeIT Encryption v6).
.BKF  Backup File (Microsoft Windows Backup Utility).
.BKG  Background image file (Many applications).
.BLANK Empty form/template file.
.BLD  BLOAD image file = Image loaded into memory with BASIC's BLOAD command.
.BLEND Blender file (Stichting Blender Foundation's Blender).
.BLF  Resource file (Shogun Total War).
.BLG  Binary-format Log file (Microsoft Windows Performance Monitor).
.BLK  Black and White/Mono color image file (Many variants).
.BLUE Blue project file (Steven Yi's Blue).
.BM   BitMagic downloaded content file (Bitmagic).
.BM   Bitmap image file (Many applications and variants).
.BM   Bookmarks file (NullSoft's WinAmp).
.BMF  Bitmap image File.
.BMI  Buzz Musical Instrument file (Buzz/Buzz Composer).
.BMK  Bookmark file (Many applications).
.BMK  Bookmark file = User generated bookmark (Microsoft Windows 3.x/9x Help systems).
.BMM  BitMagic player skin file (Bitmagic).
.BMP  Bitmap image file (Many variants, many programs). The Win/OS2 BMP file can hold pixel depths up to 32 bits and supports transparency.
.BMR  BlueMatter content Reference file (MusicMatch Jukebox).
.BMR  BlueMatter Offer file (MusicMatch Jukebox).
.BMT  BlueMatter song file (MusicMatch Jukebox).
.BMW  Buzz Song/loop without waves file (Buzz Digital Composer).
.BMX  Buzz Song/loop with waves file (Buzz Digital Composer).
.BONK Bonk audio file (MultiMediaConverters' MC Full Audio Converter).
.BOO  Boo format archive file.
.BOO  Boo language script file (NaroCAD).
.BOOPROJ Boo Project file (sharpdevelop.net's JSharp Develop 4).
.BOOT Bootscreen image file = Bitmap image.
.BOOTSKIN Stardock Bootskin boot screen.
.BP   BankPerfect file (Fabio Chelly's BankPerfect).
.BP6  Secure Profile Backup (SoftNet Security's SafeIT Encryption v6).
.BPC  BuddyPhone Contact file (BuddyPhone 2).
.BPDX Batch PDX file (Adobe Acrobat).
.BPK  C++ Builder Project file (Borland C++Builder).
.BPR  C++ Builder Project file (Borland C++Builder).
.BPS  Bullet Proof FTP Session file (Bullet Proof Software's Bullet Proof FTP).
.BR3  Bryce version 3 project file (Corel Bryce).
.BR4  Bryce version 4 project file (Corel Bryce).
.BR5  Bryce version 5 project file (Corel Bryce).
.BRC  Bryce version 2 project file (MetaCreations' Bryce).
.BRM  BRM movie plug-in file for Adobe Photoshop.
.BRO  Brochure file.
.BRO  Brochure project file (MindScape PrintMaster Gold).
.BRO  Documentation file (old Brother hardware/printer software distributions).
.BRP  O&O Defrag reports file.
.BRS  Brush file = bitmap image.
.BRT  Bryce Textures file (Corel Bryce).
.BRUSH Brush file = bitmap image.
.BSA  BackStreet download session file (Spadix Software's BackStreet Browser).
.BSC  BASIC program or archive.
.BSH  Bean Shell script file (Unix operating systems).
.BSP  Binary Space Partitioning file used in 3D world design applications and many games.
.BSP  Game map = Maps of games that employ Valve's Half-Life game engine (Valve's Half-Life/Team Fortress/Counterstrike/etcetera, games from other developers).
.BSZ  BSPlayer Skin ZIP archive file (BSPlayer).
.BTAPP BitTorrent Application file (BitTorrent's µTorrent).
.BTDNA BitTorrent DNA file (BitTorrent's µTorrent).
.BTINSTALL BitTorrent Install Package file (BitTorrent's µTorrent).
.BTKEY BitTorrent Key file (BitTorrent's µTorrent).
.BTSEARCH BitTorrent Search file (BitTorrent µTorrent).
.BTSKIN BitTorrent application Skinning file (BitTorrent's µTorrent).
.BUJ  Back-Up Job file (Personal Backup).
.BUN  Bundle file (Twelve Tone's Cakewalk).
.BUP  Backup file (Many applications).
.BUP  Bumpmap image file (Many applications).
.BUT  Button image file (Many applications, especially web site development).
.BVL  Bevel edge image file (Micrografx Picture Publisher).
.BW   Silicon Graphics Black & White image file (Many applications).
.BWA  BlindWrite Builder file (VSO Software's BlindWrite).
.BWA  Blitz World Assembler world file (Luke Hoschke's Blitz World Assembler).
.BWF  WAV audio file (QuickTime 7.7.2).
.BWG  BWG data disk project file (Jack W. Griffin's BWG Burn).
.BWI  BlindWrite Image file (Power Software's Free Any Burn).
.BWT  BlindWrite Image file.
.BZ   BZip format archive container file (Many applications).
.BZ2  BZip2 format archive container file (Many applications - BZIP.ORG).
.BZF  BZip format archive container File (Many applications).
.BZIP2 BZip2 format archive container file (Many applications - BZIP.ORG).
.BZW  BZFlag World file.
.C    C programming language source code file.
.C++  C++ programming language source code file.
.C2D  WinOnCD image file (Power Software's Free Any Burn).
.C2K  Card 2000 index card file (AS-Pro Software Card 2000).
.C2KJ Card 2000 Java applet file (AS-Pro Software Card 2000).
.C32  Card 32 index card file (AS-Pro Software Card 2000).
.C3D  Cool 3D projects file (ULEAD Cool 3D/VisualStudio and other Ulead products).
.C5F  Cameleon 5000 Formant Filter file (Camel Audio's Cameleon 5000 1.2).
.C5H  Cameleon 5000 Harmonics preset file (Camel Audio's Cameleon 5000 1.2).
.C5I  Cameleon 5000 Initialization/Reset file (Camel Audio's Cameleon 5000 1.2).
.C5I  Cameleon 5000 Instrument file (Camel Audio's Cameleon 5000 1.2).
.C5M  Cameleon 5000 Morph Envelope file (Camel Audio Cameleon 5000 1.2).
.C5N  Cameleon 5000 Noise preset file (Camel Audio Cameleon 5000 1.2).
.C5V  Cameleon 5000 Voice program file (Camel Audio's Cameleon 5000 1.2).
.C64  Commodore 64 emulator freeze/saved-state file (CCS64).
.C64  Commodore 64 graphical image file. Given how many formats are unique to the Commodore 64, the file is likely to be one of the more popular types such as Doodle, Koala, etc. (Many applications, many formats).
.C64  Commodore 64 image file (Andreas R Kleinert's SView5).
.C64  Commodore 64 program file (Many Commodore 64 emulator applications).
.C64  Commodore 64 SID chip audio file (SIDplay).
.C64  Documentation specific to the Commodore 64 operating system, Commodore 64 programs or programming, etc.
.CA   Composite Application file (IBM Lotus Symphony).
.CAB  Cabinet archive format file (Microsoft Windows and other archive applications, many variants).
.CAC  Cache file (many applications).
.CACHE Cache file (Ari Pikivirta's Home FTP Server).
.CACHE Cache file (many applications).
.CAF  Core Audio File (QuickTime and Soundtrack Pro and other audio applications).
.CAL  Calculator/spreadsheet save (Quantoid's Calc2).
.CAL  Calendar document file (Sierra On-Line's Print Artist 3).
.CAL  Calendar project file (MindScape PrintMaster Gold).
.CAL  CALS Group 4 black and white image file.
.CAL  Compressed bitmap image file.
.CAM  Camera image file (Casio cameras).
.CAR  Car/Cars data file = XCD car description format (MSB's Car Explorer).
.CAR  Quarter-fold Card project file (MindScape PrintMaster).
.CAS  Cassette tape image file = WAV/waveform audio content created by/for Radio Shack DOS/CoCo computer emulators (Nicola Salmoria & MAME team's Multiple Arcade Machine Emulator).
.CAT  Catalog file (Ashton Tate's dBase IV and other dBase and compatible database applications/developer environments).
.CAT  Security Catalog file (Microsoft Windows).
.CB   Chat room activity/conversation log file. Whether the extension was derived from the Citizen's Band radio or not, the use would be apt in this instance given CB radio communication's similarity with chat room/IRC chat activity.
.CBA  Compiled BASIC program.
.CBD  ContactBook Database file = text based (TEngel's ContactBook).
.CBL  Common Business Oriented Language/COBOL programming language source code file.
.CBM  Commodore Business Machines emulation file or emulated Commodore DOS disk image file (Style DirMaster and other Commodore computer emulators/applications).
.CBR  Captured Brush file (Boris Eyrich Software Artweaver).
.CBR  Comic Book RAR archive file (eBook applications).
.CBT  Comic Book TAR archive file (eBook applications).
.CBZ  Comic Book ZIP archive file (eBook applications).
.CC   CAMCAD document file (Many CAD/CAM applications).
.CCC  CorelCENTRAL Calendar File (Corel WordPerfect 8 Suite).
.CCD  CloneCD control file (Elaborate Bytes' CloneCD).
.CCF  Content Channel File (Go!Zilla 3.x download manager).
.CCF  CorelCENTRAL Card File (Corel WordPerfect 8 Suite).
.CCL  Credit Card Logfile (Retro Software Designs Credit Card Verifier).
.CCP  CloneCD Profile file (SlySoft's CloneCD).
.CCP  CorelCENTRAL Planner file (Corel WordPerfect 8 Suite).
.CCT  CAM Card Template file (CAM Development Business Card Designer Plus).
.CDA  Compact Disc Audio track file (Many applications and devices).
.CDA  Compact Disk digital audio.
.CDAPP Plug-in file (Safer-Networking's SpyBot Search & Destroy).
.CDC  Compact Disc jewel case Cover project file (Nero Burning ROM/Nero Express).
.CDC3 Cartes Du Ciel 3 file (Patrick Shevalley's Cartes du Ciel 3/Sky Charts 3).
.CDD  ConceptDraw Document (CS Odessa's ConceptDraw).
.CDDA AIFF audio (QuickTime 7.7.2).
.CDDA Compact Disc Digital Audio track file (Many applications).
.CDE  CD Exchange data entries file (CD Storage Master).
.CDG  Karaoke file = the video file portion that requires an audio file to accompany/play with it.
.CDI  DiscJuggler CD Image file (Power Software's Free Any Burn).
.CDJ  DiscJuggler 6 disk image file (Padus' DiscJuggler 6).
.CDL  CADL section entities file (CadKey and other CAD/CAM applications).
.CDL  ConceptDraw Library file (CS Odessa's ConceptDraw).
.CDLX CD Layout file (Adobe Audition).
.CDR  CorelDRAW vector format image file (CorelDRAW and many other graphics applications).
.CDS  C-Organizer Database file (CSoftLab C-Organizer 2001).
.CDS  Cadrans Solaires fichiers = Sundial file (Francois Blateyron's Shadows).
.CDS  Native CD catalog Storage database file (CD Storage Master).
.CDT  ConceptDraw Template file (CS Odessa's ConceptDraw).
.CDT  CorelDRAW Template image file (CorelDRAW, CorelDesigner).
.CDW  ConceptDraw Workspace file (CS Odessa's ConceptDraw).
.CDX  Compound Index file (Microsoft Visual FoxPro 6).
.CDX  CorelDRAW Compressed image file (Corel's CorelDRAW).
.CEDCOVERS Cover Editor Designer Covers file (Ashampoo Burning Studio).
.CEDPRJ Cover Editor Designer Project file (Ashampoo Burning Studio).
.CEDTHEME Cover Editor Theme file (Ashampoo Burning Studio 11).
.CEL  Celestia script (3 dimensional celestial emulation application).
.CEL  Cool Edit audio Loop file (Cool Edit Pro).
.CEL  FLC animation (QuickTime 7.7.2).
.CEL  Flic animation Cel format image (Autodesk Animator and other image applications).
.CER  Certificate document file (Sierra On-Line's Print Artist 3).
.CER  Certificate project file (MindScape PrintMaster).
.CER  Security Certificate file (Microsoft Windows cryptographic tasks).
.CFG  Application skin file (Draw3D).
.CFG  Hardware Configuration file (Many applications).
.CFG  Instructional documentation for configuring applications/devices = Text files (Software distributions).
.CFG  Program Configuration file (Many applications).
.CFM  Cold Fusion Markup Language file (ColdFusion and other webmastering applications).
.CFML Cold Fusion Markup Language file (ColdFusion and other webmastering applications).
.CFP  CD-RTools Front-End Project file (O. Valencia's CDRTools Front-End/CDRTFE).
.CFS  CFScript snippet file (Allaire ColdFusion).
.CGA  Ulead CG Animation library file (Ulead CG Infinity).
.CGE  Ulead CG Envelope library file (Ulead CG Infinity).
.CGI  Common Gateway Interface file = Perl language script (Many applications).
.CGM  Computer Graphics Metafile format image file (Many graphics applications).
.CGO  Ulead CG Object file (Ulead CG Infinity).
.CGO  Ulead CG Style library file (Ulead CG Infinity).
.CGP  Captor Group file (StileSoft NetCaptor 6.5).
.CGZ  Compressed CGM image file (Many graphics applications).
.CH3  Harvard Graphics format image.
.CHA  Change sets file (Cincom VisualWorks SmallTalk).
.CHA  Character file.
.CHA  Color Channel mixture adjustment file (Adobe Photoshop).
.CHI  ChimpNotes file (Demios' Chimp Notes).
.CHIMPNOTES ChimpNotes file (Demios' Chimp Notes).
.CHL  Chain Launching jobs file (Greatis' RegRun Security Suite 3).
.CHM  Compiled HTML format help file (Many applications).
.CHP  ChimpNotes v1 file (Demios' Chimp Notes).
.CHR  Bitmap Character set = single image containing a monospaced character set (Many applications, games in particular. Many variants).
.CHR  Character set file (Borland C++ applications).
.CIF  CD Image File (Adaptec Easy CD Creator 3).
.CIF  Easy CD/DVD Creator Image File (Power Software's Free Any Burn).
.CIN  Channel Information file (GTek).
.CIN  Kodak Cineon format image file (CinePaint and other graphics/animation applications).
.CIR  SPICE Circuit/schematic file.
.CIRC Ciruit project file (Logsim).
.CIT  Citation/Citations file (Many applications).
.CIT  CITI file.
.CITI CITI circuit file.
.CIX  Code Intelligence XML file (ActiveState's Komodo Edit).
.CL   Class file.
.CL   Cursor Library file (Aha-Soft's IconUtils ArtCursors).
.CL   Lisp source code file.
.CL3  CD Layout file (Adaptec Easy CD Creator 3).
.CLA  Class file (Cincom VisualWorks SmallTalk).
.CLASS Java Class file (Many Java applications).
.CLB  Color Book file (QuarkXPress Passport).
.CLG  Catalog file of WIM file (Windows System Image Manager).
.CLISP Lisp source code file.
.CLJ  Clojure source file.
.CLK  Image file (Corel R.A.V.E.).
.CLONEDVD CloneDVD 2 project file (Elaborate Bytes' CloneDVD 2).
.CLP  Clipboard clipping = Saved clipboard objects (Windows ClipBook Viewer and other applications).
.CLR  Color settings file (MindScape PrintMaster).
.CLS  Classlist description file (Microsoft's series of Flight Simulator games - many variants).
.CLV  ClearVideo video file.
.CMAKE CMake project file.
.CMB  Combat Mission game-save/scenario Battle file (Big Time Software's Combat Mission).
.CMD  FastLynx 2 form file = command script (Sewell Development's FastLynx 2/3).
.CMD  Command/CMD.exe batch file = Batch/BAT file. The only difference between CMD and BAT is the extension and that Windows NT variants do not have access to a real MS-DOS (NT-based Windows operating systems).
.CMIS Page Critic Mission file (FirstPlace Software's WebPosition Gold).
.CMO  CyberMotion 3D object project file (CyberMotion 3D-Designer 6).
.CMP  Lead CMP image file = Lead JPEG (Graphics editors/applications).
.CMX  Corel Metafile Exchange file.
.CMX  Corel Presentations Exchange format file (Corel Word Perfect Office X6).
.CNF  Conferencing speed-dial shortcut file (Microsoft Windows).
.CNO  Conference file (CIX's Ameol2).
.CNT  Contents file for Windows HLP document (Microsoft Windows Help).
.COB  Caligari trueSpace 3D Object file (Caligari Truespace, Bryce, and other 3D editors/viewers).
.COL  Collection file (Invention Pilot's Silver Pilot).
.COLLECTION Collection file = Text or binary (Paul Boersma's and David Weenink's Praat linguistics research software).
.COLOR Color gradient file (Neuber Font Twister).
.COM  COM application file (Windows operating system).
.COMPOSITEFONT Composite Font file (Corel Word Perfect Office X6).
.CONF Configuration file (Many operating systems, applications and variants).
.CONFIG Confuguration file (Many applications and variants).
.CPG  Calypso Plug-in file (Micro Computer Systems' Calypso e-mail client).
.CPIO CPIO format archive container file (Many applications).
.CPK  Copernic engine Package file (Copernic 2000).
.CPL  Control Panel object file (Microsoft Windows).
.CPN  Campaign file (Microsoft's Age of Empires 2).
.CPP  C++ and C# programming source code file (Many C++ and C# development environments and compilers).
.CPSH Color Pixel Shader file (Ashampoo Burning Studio).
.CPT  Corel PHOTO-PAINT 6 & 7 bitmap image file (Corel PHOTO-PAINT, CorelDRAW X6, and other graphics applications).
.CPX  Corel ArtShow image file (Corel ArtShow).
.CR2  Canon RAW v2 format image file.
.CRD  Card file (Microsoft Windows 3.x/9x/ME).
.CRD  Contact events markup (ICQ2000a).
.CRF  CDCheck diagnostic, reliability, error Report File (CDCheck). CDCheck developer began employing this extension and ceased using .CDF when it was discovered other products used the .CDF extension.
.CRF  Crafts document file (Sierra On-Line's Print Artist 3).
.CRL  Certificate Revocation List file (Many applications/operating systems).
.CRL  Certificate Revocation List file (Microsoft Windows).
.CRON Crontab file (ActiveState's Komodo Edit).
.CRP  Crop files (SimFarm game).
.CRT  Commodore 64 auto-starting Cartridge ROM or utility Cartridge (Most good C64 emulators).
.CRT  Crate file (Allaphs' CrateSim).
.CRW  Canon RAW format image file.
.CRX  Chrome Extension file (Axure RP Pro).
.CS   C# code/script file (sharpdevelop.net's JSharp Develop 4).
.CS   C# programming language source code (Microsoft VisualStudio).
.CS0  Calendarscope planner/scheduler data file (Duality Calendarscope).
.CSD  CSound orchestra file (Algorithmic composition applications that employ the CSoundAC API, CSoundQt).
.CSD  CSound score file (Algorithmic composition applications that employ the CSoundAC API, CSoundQt).
.CSF  IGC Content Sealed Format file = Proprietary encrypted redactable CAD/document delivery format (IGC's Brava Desktop and Brava/Free DWG Viewer).
.CSH  C Shell script file (Many Unix/Linux operating systems, Bill Joy's C shell command line interface).
.CSH  Custom Shape file (Adobe Photo Elements).
.CSK  Copernic Skin file (Copernic 2000).
.CSL  Corel Symbol Library file (CorelDRAW X6 and other Corel products).
.CSM  Cartography Shop Map file (Cartography Shop).
.CSM  CShop Map file (Leadwerks 3D World Studio).
.CSO  CSound orchestra file (Algorithmic composition applications that employ the CSoundAC API, CSoundQt).
.CSPROJ C# Project file (sharpdevelop.net's JSharp Develop 4).
.CSPROJ C++ Source code Project file (Microsoft VisualStudio).
.CSQ  Client-Server Query Wizard file = SQL Query for OBDC databases (Microsoft's Visual FoxPro 2.6).
.CSS  Cascading Style Sheet markup/code file (Many document applications, especially web document/development applications).
.CST  Crosti cross-stitch Scheme Template file (Levin Sergey's Crosti).
.CSV  Comma Separated Values file = data sharing/verification file format (Many applications).
.CSV  Comma Separated Values spreadsheet file (Draw3D).
.CSZ  Skin ZIP archive file (TCMP).
.CT   SciTex Continuous Tone image file (Many graphics applications).
.CT2  CreaToon 2 scene file (Androme CreaToon 2).
.CTB  CTB file (AutoDWG's PDF Converter).
.CTF  Catalog File (WhereIsIt?).
.CTG  Catalog Group file (WhereIsIt?).
.CTI  Completed Task list file (Pollen's Task-O-Matic).
.CTM  Catalog Template file (WhereIsIt?).
.CTX  CreaToon Extension file (Androme CreaToon 2).
.CTY  City file (Maxis' SimCity, SimCity for Windows).
.CUE  Cue sheet file (Many audio and other applications).
.CUE  Disc image (Many applications).
.CUE  Optical media image Cue file (Many applications).
.CUI  Color UI file (Quark's CopyDesk and other Quark products).
.CUJ  Clean-up Job file (Personal Backup).
.CUL  Cursor Library file (Cursor Arts' IconForge 6).
.CUR  Cursor file (Hagen Wieshofer's Icon Edit Pro).
.CUR  Static Cursor image file (Microsoft Windows and other icon/cursor applications).
.CUT  Dr. Halo image file (Many image applications).
.CUX  CUX image file (ACDSee).
.CVF  Compressed Volume File (Many applications).
.CVG  Calamus Vector Graphics file (Calamus).
.CVL  Convolution kernal settings file (Adobe Systems' Premiere and other Adobe Systems' products).
.CVR  Cover page file (ElectraSoft 32bit Fax 9).
.CVSH Color Vertex Shader file (Ashampoo Burning Studio).
.CW_  Corel Workspace file (Corel's CorelDRAW X6).
.CXF  QCad font file (LibreCAD).
.CXN  Conference file (CIX's Ameol2).
.CXT  Crayola file (IBM Crayola Print Factory).
.CXX  C++ programming language source code file.
.D    DigitalMars D file = text/code.
.D2M  Creative Micro Devices FD2000 emulator image file (Style DirMaster and other applications).
.D3D  Draw3D format file (Draw3D).
.D3D  Ray Dream Studio version 3 object (MetaCreations Ray Dream Studio).
.D3D  Ray Dream Studio version 3 object (MetaCreations Ray Dream Studio).
.D41  Commodore 1541 disk drive image used by Commodore computer emulators.
.D64  Commodore 1541 disk drive image used by Commodore computer emulators.
.D64  Commodore 1541/2031/1551 disk drive format image file (Salmoria & MAME team's Multiple Arcade Machine Emulator).
.D71  Commodore 1571 disk drive image file (MAME, CCS64, VICE, and other computer emulators).
.D71  Commodore 1571 disk drive image used by Commodore computer emulators.
.D80  Commodore 8050 disk drive image used by Commodore computer emulators.
.D81  Commodore 1581 disk drive image used by Commodore computer emulators.
.D81  Commodore 1581/1565 disk drive image file (MAME, CCS64, VICE, and other computer emulators).
.D82  Commodore 8250 dual disk drive image used by Commodore computer emulators.
.DAA  Direct Access Archive file (Power Software's Free Any Burn).
.DAE  Collada file (Timothy M Shead's K-3D 0.8).
.DAE  Digital Asset Exchange/Collada file.
.DAF  Data File (Integra Computing's BillPower).
.DAM  Dammen/draughts game file = single game. Dammen is the Netherlander's name for the game of Draughts (Harm Jetten's DAM).
.DAO  Disc At Once image file (Many image writer/creator applications).
.DAT  DAT or ADAT raw audio file.
.DAT  Data file (Many applications and formats).
.DAT  Dataset file (Many applications, many variants).
.DAT  Disk image file (Helix Software's Nuts & Bolts and other applications, many variants).
.DAT  Playlist file (MusicMatch Jukebox).
.DAT  Video CD/VideoCD/VCD DAT format video (Many applications and devices/appliances).
.DB-JOURNAL Temporary notebook backup Journal file (Cinta Software's CintaNotes).
.DB   CintaNotes Notebook or CintaNotes Notebook backup file (Cinta Software's CintaNotes).
.DB   Paradox format Database file (Many applications).
.DB3-JOURNAL Font service Database Journal file (High-Logic Main Type).
.DB3  Font Database file (High-Logic Main Type).
.DB3  Icon Database file (BauerApps RightNote Icon Manager).
.DBB  DeBabelizer BatchList file (Equilibrium's DeBabelizer 5).
.DBC  Database file (Microsoft Visual FoxPro 6).
.DBF  Database File (FoxPro 2, Visual FoxPro, FoxBASE).
.DBF  dBase format database File (Many applications).
.DBF  dBase II-IV Database File format.
.DBF  dBase V database file. Most applications, including dBase, used DBF files for a multiplicity of purposes, and not merely to store raw database entry data. Calling these files a resource file, configuration file, audio file, etcetera would not be improper if that is what they contained (Ashton Tate's dBase and it's many imitators, fanboys, etcetera, many variants).
.DBI  Database Index file.
.DBI  Database Interface file.
.DBI  DeepBurner backup index file (Astonsoft's DeepBurner 1.9).
.DBL  64-bit Doubles file = RAW audio (Cool Edit Pro).
.DBML Database Markup Language file (Microsoft Visual Studio Tools for Applications 2.0).
.DBO  DarkBasic Object file (Leadwerks 3D World Studio).
.DBP  DeBabelizer SuperPalette file (Equilibrium's DeBabelizer 5).
.DBPAS Auto-save DBPAS file (Andrey M. Zubarev's ZCAD).
.DBPAS DBPAS file (AutoDWG's PDF Converter).
.DBR  DeepBurner CD/DVD authoring project file (Astonsoft's DeepBurner 1.9).
.DBS  DeBabelizer Script file (Equilibrium's DeBabelizer 5).
.DBT  dBase memo Text file (Database applications).
.DC   DesignCAD file (Upperspace's DesignCAD 97/2000/3000).
.DC2  DesignCAD 2D ASCII file (Upperspace's DesignCAD 3D MAX).
.DC3  DesignCAD 3D ASCII file (Upperspace's DesignCAD 3D MAX).
.DCD  DesignCAD Drawing file (Upperspace's DesignCAD 3D MAX).
.DCH  DesignCAD Custom Hatch pattern file (Upperspace's DesignCAD 3D MAX).
.DCL  SGML Declaration file.
.DCS  Duplicatch Session file (Analinx Duplicatch).
.DCT  DesignCAD Custom Toolbox file (Upperspace's DesignCAD 3D MAX).
.DCT  Dictionary file (QuarkXPress and many other applications).
.DCX  Multi-image PCX format file (Intel SatisFAXtion, ElectraSoft 32bit Fax 9, and other fax or graphics applications).
.DCX  Multi-page paintbrush format image (ZSoft Publisher and other applications).
.DD   Doodle format image (Commodore 64 Doodle image editor native format).
.DDD  Diagram Designer Diagram file (MeeSoft Diagram Designer).
.DDF  Disk Data File (ACD Systems ACDSee).
.DDF  Disk Data File = thumb data (ACD Systems' ACDSee).
.DDF  Music library file (MusicMatch Jukebox).
.DDS  DDS texture file (Martin Wright's DXTBmp Editor - Many format variations).
.DDS  Direct Draw Surface file (Many graphics applications).
.DDT  Diagram Designer Template palette file (MeeSoft Diagram Designer).
.DEC  Decision file (Business Game Builder).
.DECTEST Decimal Test file (Franz Schmid/Scribus Team Scribus).
.DEF  Delphi source code.
.DEL  Deleted entries file = text removed from another text file.
.DELAYOUT Disketch disk label layout (NCHSoftware Disketch Disk Label).
.DEM  Demo file (C Jain's Mountain 3D).
.DEM  Demo file (Many applications).
.DEM  Digital Elevation Model file = topographical elevation data. (Many applications. Many variations including USGS, GTOPO30, VistaPro, etc.).
.DEN  Deneba file (Deneba).
.DEP  Dependency file (Many applications).
.DEP  Dependency file (Microsoft Office).
.DEPROJ Disketch Disk Label Project file (NCH Software's Disketch Disk Label).
.DES  Designer image file (Corel Designer).
.DEX  Disketch Disk Label file (NCH Software's Disketch Disk Label).
.DFM  Delphi application resource file.
.DFX  Micrografx image effects file (Micrografx Picture Publisher).
.DHD  Creative Micro Devices/CMD Hard Drive emulator image file (Style DirMaster and other applications).
.DHK  Diffie Hellman Key exchange protocol file = 2048 bits (SoftNet Security's SafeIT Encryption v6).
.DHP  Creative Micro Devices/CMD Native Partition emulator image file (Style DirMaster and other Commodore operating system emulator applications).
.DHT  Dynamic HTML/DHTML file (Many browser/server/web development applications).
.DIB  OS/2 Device Independant Bitmap image file (Many applications).
.DIC-SDS Dictionary Smart Diary file (Programming Sunrise's Smart Diary Suite 4).
.DIF  Data Interchange Format file (Many database, worksheet/spreadsheet applications).
.DIF  Device Information File (device driver installers for SiS, Cmedia, and other vendor hardware).
.DIF  Difference file for comparisons, merging (Many applications).
.DIF  DV movie (QuickTime 7.7.2).
.DIF  Torque map file (Leadwerks 3D World Studio).
.DIG  Digital audio file (SoundDesigner and other applications).
.DISCO Web service Discovery file (Microsoft VisualStudio).
.DISPOSITION Disposition file (jOrgan).
.DIY  Do It Yourself file = Text instructions that accompany device driver software installation packages that provide information for manual device driver installation (Samsung and other hardware manufacturers).
.DIZ  Description In ZIP file = A short description of a ZIP archive's contents stored within the ZIP file itself. The file facilitates automated archive content description building facilities that exist in unattended file managing/sharing systems such as FTPs, electronic bulletin boards, etcetera. The extracted ZIP file descriptions are exposed to those using the system if they wish to view archive descriptions of archives available for download. The use of DIZ files now extends to any archive file the automated/unattended systems support (Many applications).
.DJV  AT&T DjVu encoded file (Many document viewers, fewer editors).
.DJV  DJVU format document (WinDJView and other applications).
.DJVU AT&T DjVu encoded file (Many document viewers, fewer editors).
.DJVU DJVU format document (WinDJView and other applications).
.DKF  DesignCAD binary Keyboard File (Upperspace's DesignCAD 3D MAX).
.DLL  Dynamic Link Library file = application resource library (Microsoft Windows and many Windows applications).
.DLL  Faces file (nFX Cartoon-O-Matic).
.DLX  DLX file (HollywoodFX).
.DMA  DMOD format audio file (UltraCo UltraPlayer 1).
.DMDF DMD Font file (Future Pinball).
.DMF  DeleD Map File (Delgine Team DeleD 3D Editor).
.DMF  DesignCAD binary Menu File (Upperspace's DesignCAD 3D MAX).
.DMG  Macintosh image file (Power Software's Free Any Burn).
.DMI  Default Messages file (David Harris' Pegasus Mail).
.DMP  Download Management Protocol (Go!Zilla 3.x download manager).
.DMS  DiskMasher disk image format file (DiskMasher).
.DMU  DMOD format URL file (UltraCo UltraPlayer 1).
.DNA  DNA file = function values (MediaChance Real-DRAW).
.DNC  IGESToolbox file (IGESToolbox).
.DNG  Digital Negative file (Many applications and now cameras and other hardware).
.DOC  Draughts DOC-format game(s) file (Turbo DamBase, Truus, and other draughts games).
.DOC  Microsoft Word document (Microsoft Word and many Office applications).
.DOC  Microsoft Word Mail Merge document (Microsoft Word and many Office applications).
.DOC  Text documentation (Many applications).
.DOC  Word Document file (Corel Word Perfect Office X6).
.DOCM Microsoft Word Macro-enabled Document file (Microsoft Word).
.DOCX Word DOCX Document file (Word Perfect Office X6).
.DOF  Delphi file.
.DOS  Disk Operating System/DOS configuration file = text (Many DOS applications).
.DOT  Document Template file = Microsoft Word format (Microsoft Word and many other Office applications).
.DOX  Multi-Mate format document file (Many word processors/Office applications).
.DPA  DVD Project file (MGI VideoWAV 3).
.DPF  DeleD Prefab File (Delgine Team DeleD 3D Editor).
.DPL  Data Display file (Michael Margraf's QUCS/Quite Universal Circuit Simulator).
.DPP  DrawPlus drawing Project file (Serif's DrawPlus).
.DPR  Delphi Project file (Microsoft Developer Studio 6).
.DPR  Delphi Project file.
.DPS  Presentation file (Kingsoft Office Presentation).
.DPT  Presentation Template file (Kingsoft Office Presentation).
.DQY  Database Query file (Microsoft Excel).
.DRG  Card database file (Avancesoft RGS-Cardmaster).
.DRP  Redrum drum machine device patch file (Propellerhead's Reason).
.DRV  Driver files for hardware devices (Microsoft Windows).
.DRW  Micrografx Drawing 3 format image file (Micrografx Designer, Micrografx Draw 3).
.DS   DrumSynth instrument file (DrumSynth).
.DS4  Micrografx Designer v4 image file (Micrografx Designer 4).
.DS7  Saved game file (Nihon Falcom's Lord Monarch - Online version).
.DSF  Designer format image File (Micrografx Designer 5).
.DSF  DVD Slim Free cover design project file (Elefant Software's DVD Slim Free).
.DSK  Disk dump file (MAME and MESS).
.DSN  Design file (Matt Pyne's TinyCAD).
.DSP  Developer Studio Project file (Microsoft Developer Studio 6).
.DSP  Digital Signal Processor plug-in file (Audio players).
.DSPP Digital Signal Processor Plug-in file (Audio players).
.DSQ  Device Standard Quality parameter presets file (MGI VideoWave 1.5).
.DSW  Developer Studio Workspace file (Microsoft Developer Studio 6).
.DTD  Document Type Definition files which describe or define the content of the file itself and/or other files (Many applications, many formats/variations).
.DV   Digital Video format video file (Many video applications, Sony video cameras, and other devices).
.DVA  DVDAuthor project file (DVDAuthor GUI).
.DVAM DVDAuthor Menu file (DVDAuthor GUI).
.DVD  DVD Project file (Andrej Rakar's Simple DVD Creator).
.DVDFAB5 DVDFab5 file (Fengtao Software's DVDFab).
.DVDFAB6 DVDFab6 file (Fengtao Software's DVDFab).
.DVDFABBLURAY2BLURAY DVDFab BluRay To BluRay project file (Fengtao Software's DVDFab).
.DVDFABBLURAY2DVD DVDFab BluRay To DVD project file (Fengtao Software's DVDFab).
.DVDFABBLURAY2MOBILE DVDFab BluRay To Mobile device project file (Fengtao Software's DVDFab).
.DVDFABBLURAY2MOBILE3D DVDFab BluRay To Mobile device project file (Fengtao Software's DVDFab).
.DVDFABBLURAYDECRYPT DVDFab BluRay Decryption project file (Fengtao Software's DVDFab).
.DVDFABDVD2DVD DVDFab DVD To DVD project file (Fengtao Software's DVDFab).
.DVDFABDVD2MOBILE DVDFab DVD To Mobile device project file (Fengtao Software's DVDFab).
.DVDFABDVDDECRYPT DVDFab DVD Decryption project file (Fengtao Software's DVDFab).
.DVDFABFILE2BLURAY DVDFab File To BluRay file (Fengtao Software's DVDFab).
.DVDFABFILE2DVD DVDFab File To DVD file (Fengtao Software's DVDFab).
.DVDFABFILE2MOBILE DVDFab File To Mobile device file (Fengtao Software's DVDFab).
.DVDFABFILEMOVER DVDFab File Mover project file (Fengtao Software's DVDFab).
.DVDFABMOBILE2DTO3D DVDFab 2D To 3D Conversion project file (Fengtao Software's DVDFab).
.DVDS DVD Styler project file = XML markup (DVD Styler v2.3 rc3).
.DW3  Draw3D file (Draw3D 1, Click3D 1).
.DW3  DreamWeaver 3 file (Macromedia Dreamweaver 3).
.DWD  DiamondWare Digitized audio/sample file.
.DWF  Design Web Format file (Autodesk DWF Viewer).
.DWFX Design Web Format XML file (IGC Free DWG Viewer and other applications).
.DWG  AutoCAD Drawing file = proprietary, native AutoCAD drawing format (Autodesk's AutoCAD).
.DWL  Locked DWG Drawing file (AudoDWG's DWGSee).
.DWP  DarkWave Project file (ExperimentalScene's DarkWave Studio).
.DWS  DesignCAD Workspace file (Upperspace's DesignCAD 3D MAX).
.DWT  Dreamweaver Template file (Dreamweaver).
.DXF  Drawing Interchange Format image file = 2D and 3D drawing entities and their attributes (AutoCAD and other 3D/CAD/graphics applications).
.DXF  QCad 1.x file (LibreCAD).
.DXP  CDBurnerXP project file (Canneverbe CDBurnerXP).
.DXP  Dexpot saved application profile (Dexpot).
.DXS  DeleD XML Scene file (Delgine Team DeleD 3D Editor).
.DXX  DXF format Extract file (CorelCAD).
.E    Eiffel file = text/code.
.EAC3 AC3 audio format AKA A/52 (Many media applications).
.EAF  ELAN Annotation File = XML markup (Audio transcription files).
.EBC  EBCDIC text document file (Many text applications).
.EBML Extensible Binary Meta Language file.
.ECC  Error-Correction Codes file = Reed-Solomon ECC (ICE Graphics' ICE ECC).
.ECP  Easy Code Project file (Ramon Sala's Easy Code GoASM).
.ECR  Easy Code Resource file (Ramon Sala's Easy Code GoASM).
.ECW  Easy Code Window file (Ramon Sala's Easy Code GoASM).
.EDB  Microsoft Exchange server store Data Base file (Microsoft Exchange Server).
.EDL  Adobe Premiere Edit Decision List/EDL script file (SoftLab's DDClip Pro).
.EDL  Edit Decision List/EDL file (Adobe Premiere 5).
.EDS  EditStudio document/project file = text XML (Pure Motion EditStudio).
.EDT  EditStudio template file = text XML (Pure Motion EditStudio).
.EFX  OpenFX Effects file (OpenFX Animator).
.EI   Electric Image format image file (Electric Image).
.EL   Lisp source code file.
.ELEV WCS Elevation file = terrain height data (3D editors and mapping applications).
.ELM  Theme Elements package file (Valadeo LiveSite Creator).
.ELX  Event Log Explorer workspace file (FSPro Labs' Event Log Explorer 4).
.EMAILFERRETSEARCH EmailFerret saved Search file (EmailFerret).
.EMF  Enhanced Meta File image or icon file (Many applications).
.EML  E-Mail file (Netscape Mail, SoftMaker Office eM Client, and other e-mail applications).
.EMULECOLLECTION eMule/ED2K file links Collection file (eMule-Project's eMule, eMule mods, and compatible filesharing clients).
.ENC  Encoded file requiring decoding, usually text-based/MIME encoding (Many applications).
.ENFF  Extended Neutral File Format file = an adaptation of Eric Haines' NFF format file.
.ENG  English language/language-support file = documentation, translation(s), dictionary, application library, etc.
.ENG  RASP motor/engine file (OpenRocket and rocket simulators).
.ENT  Character Entities set file (Word Perfect Office X6).
.ENT  Dial-up networking Entries file (Magenta's DUN Manager).
.ENT  Entities file (CAD/CAM and prototyping applications).
.ENV  Envelope document file (Sierra On-Line's Print Artist 3).
.ENV  Envelope file (HollywoodFX Incorporated Hollywood FX).
.ENV  Envelope project file (MindScape PrintMaster).
.EOS  Enfish Onespace Skin file (Enfish Personal).
.EP   Encapsulated PostScript vector based drawing (Many variants, many programs).
.EPA  Award BIOS logo image file = displayed on bootup by a multitude of personal computers that use it's BIOS chips.
.EPC  Encapsulated/Ember Photo Collection file (Firehand Ember).
.EPI  Encapsulated PostScript Interchange format file = an EPS file with a prepended bitmap thumbnail image of what the EPS/EPSI page will look like when printed (Many applications).
.EPL  Earjam Playlist file (Earjam Internet Music Player 1.x).
.EPS  Encapsulated PostScript format file = Developed by Adobe and used extensively in printing, publishing, etcetera (Many applications).
.EPSF Encapsulated PostScript vector based drawing (Many variants, many programs).
.EPSI Encapsulated PostScript Interchange format file = an EPS file with a prepended bitmap thumbnail image of what the EPS/EPSI page will look like when printed (Many applications).
.EPT  Encapsulated PostScript vector based drawing (Many variants, many programs).
.EPUB Electronic Publication format document file (Document/eReader viewers/editors).
.ER   Elastic Reality effects file (Avid Elastic Reality).
.ER   Entity/Relationship table diagram (Dia and other diagramatic applications).
.ERL  Erlang programming language file = text/code (Many applications "werl.exe").
.ERP  Easy Resource Planner database (Patrena's Easy Resource Planner).
.ERR  Error log (SimCity for Windows and other applications).
.ERR  Program compiling Error log (Microsoft Visual FoxPro).
.ERT  Entity/Relationship Table diagram (Dia and other diagramatic applications).
.ESL  Quickstart file (IBM Crayola Print Factory).
.ESQ  Esquimo 3D file (Nine Vectors' Esquimo 3D).
.ESS  EasySpeadSheet Spreadsheet file (e-Press Easy Office).
.EST  E-Soft song Set file (E-Soft's Media Box MP3 Workstation).
.EST  Spanish/Espańol language file for Unreal Tournament 2003 (Digital Extremes & Epic Games UT2003).
.ET   Spreadsheet file (Kingsoft Office Spreadsheets).
.ETICOVERNOTE Enfish Cover Note file (Enfish Onespace Personal).
.ETIQUICKNOTE Enfish Quick Note file (Enfish Onespace Personal).
.ETL  Circular or sequential Trace Log file (Microsoft Windows Performance Monitor).
.ETT  Spreadsheet Template file (Kingsoft Office Spreadsheets).
.EULA End User Licensing Agreement file = text file that accompanies software and other distributions that presumes that any sap reading it or performing any act described in it is entered into an agreement with unknown and unseen parties by an act of miraculous conceptualizing by said parties.
.EVY  Corel Envoy document (old WordPerfect application suites and applications/systems of that era that supported Envoy applications).
.EXE  Executable application file (Windows operating system).
.EXE  Script droplet file (Adobe ImageReady).
.EXE  Self-extracting archive (Many variants and applications).
.EXP  Export template file (abcAVI Tag Editor).
.EXR  OpenEXR high definition image file (LuminanceHDR).
.EXSD Extension Schema Definition file (IBM Lotus Symphony).
.EZB  EasyBookkeeper file (e-Press Easy Office).
.EZP  Easy Web Page Creator Web Site file (e-Press Easy Office).
.EZP  EasyPresentations Presentations file (e-Press Easy Office).
.F    Formula Translation/Fortran programming language source code file.
.F2K  Fortran programming language source code file.
.F35  3.5 inch Floppy disk image file (TeraByte BootIt Bare Metal).
.F77  Formula Translation/Fortran 77 programming language source code file.
.F90  Formula Translation/Fortran 90 programming language source code file.
.F95  Formula Translation/Fortran 95 programming language source code file.
.FABPFPKG DVDFab Downloadable Profile Package file (Fengtao Software's DVDFab).
.FAN  form-Z Animation file (form-Z RadioZity).
.FARCONFIG Far Manager Configuration file (Far Manager).
.FAT  FreshView web markup Template (FreshDevices FreshView).
.FAV  Favorites file (Microsoft Outlook/Outlook Express).
.FAX  Fax cover sheet project file (MindScape PrintMaster Gold).
.FAX  Fax document (602Software 602Photo Image).
.FAX  Generic FAX image file = G3 1-D encoded (Many FAX devices and FAX/graphics applications).
.FAX  GFI Fax file (GFI FaxMaker).
.FB   FreeBASIC file (FreeBASIC IDE).
.FB2  Fiction Book version 2 file (Fiction Book, Document/eReader viewers/editors).
.FBA  FinalBurner Audio CD project file (ProtectedSoft's FinalBurner).
.FBD  FinalBurner Data CD/DVD project file (ProtectedSoft's FinalBurner).
.FBL  File Backup List file (Golden Hawk Technology CDRWin).
.FBP  FreeBASIC Project file (KetilO's FbEdit FreeBASIC Editor).
.FBS  FreeBASIC Session file (FreeBasic IDE).
.FBV  FinalBurner DVD project file (ProtectedSoft's FinalBurner).
.FCD  Virtual CD-ROM image file (Power Software's Free Any Burn).
.FCD  FidoCad file (David Bucci's FidoCadJ).
.FD   FD font file (IGC Free DWG Viewer).
.FDB  FDB Flash format Font file (Ming).
.FDF  Forms Document File (Adobe Acrobat and compatible applications).
.FENCELAYOUT Fence Layout file (Stardock Fences 2).
.FFD  ffDiaporama project file (Dominique Levray's ffDiaporama).
.FFF  Form Fact File (David Harris' Pegasus Mail).
.FFO  File Info file (Adobe Photoshop 5).
.FFPRESET FFMPEG Presets file (FFMPEG, Dominique Levray's ffDiaporama).
.FFT  FFT format Font file (Many applications).
.FFT  Font FX Template file (Electric Rain Font FX).
.FFX  Font FX project file (Electric Rain Font FX).
.FH   Freehand document file (Macromedia's Freehand).
.FH5  Freehand 5 document file (Macromedia Freehand 5).
.FH7  Freehand 7 document file (Macromedia Freehand 7).
.FH8  Freehand 8 document file (Macromedia Freehand 8).
.FH9  Freehand 9 document file (Macromedia Freehand 9).
.FHX  Freehand Xtras file = Freehand executable extension/add-in (Macromedia Freehand, many variants).
.FIG  Figure drawing format native to UNIX system's Xfig programs.
.FILES Project Files list file = filename.CFP.FILES (O. Valencia's CDRTools Front-End/CDRTFE).
.FIN  Find file (Corel's CorelDRAW X6).
.FIO  File Input/Output file = Dynamic Link Library/DLL file, occasionally referred to as filters (Ulead Systems' products).
.FIRE Firestarter project file (CoffeeCup Firestarter).
.FIT  FITS images file.
.FKC  FBackup Catalog file = SQL database (Softland FBackup 4).
.FKC-JOURNAL FBackup Catalog Journal file (Softland FBackup 4).
.FKY  FoxPro Keyboard macro file (Microsoft Visual FoxPro 6).
.FLA  Flash movie (Macromedia Flash and Flash supporting applications).
.FLA  Free Lossless Audio Codec audio file (Many audio players, editors, and other applications).
.FLAC Free Lossless Audio Codec audio file (Many audio players, editors, and other applications).
.FLC  Flic animation file (QuickTime 7.7.2).
.FLC  Flic animation file (Autodesk Animator and other image applications).
.FLF  Encapsulated Photo Collection file (Firehand Ember).
.FLG  Upgrade FLG file (ZedTech's ZTreeWin).
.FLI  8-bit FLI static image file.
.FLI  Flic animation (QuickTime 7.7.2).
.FLI  Flic animation file (Autodesk Animator and other image applications).
.FLL  FoxPro Library file (Microsoft Visual FoxPro 6).
.FLM  Filmstrip file (Adobe Systems' Photoshop/Premiere/Photo Elements).
.FLO  Flowcharter image file = EMF file (MicroGraphx Flowcharter).
.FLP  Floppy disk image file (Power Software's Free Any Burn).
.FLP  FruityLoops sample Loop/song file (Image-Line FruityLoops Pro).
.FLT  Filter file (Corel's CorelDRAW X6).
.FLT  OpenFlight 3D scene description format file (MultiGen OpenFlight databases and many visual simulation applications).
.FLV  Flash Video file (Macromedia Flash and many video applications).
.FLX  AutoDesk 16-bit animation file (Ulead CG Infinity and many other applications).
.FLX  FLX application data file (Diskboss).
.FLX  FLX drawing file (CorelCAD).
.FLY  Flyerclip image or image sequence file (Hervé Adam's Aura).
.FMD  FantaMorph Data file (Abrosoft's FantaMorph 5).
.FMF  Font Metrics File.
.FMK  FaxMaker output link file (GFI FaxMaker).
.FML  Formula file = Mathematical formula.
.FMP  Fontmap/Fontmappings file (Many applications).
.FMP  FantaMorph Project file (Abrosoft's FantaMorph 5).
.FMS  FantaMorph Skin file (Abrosoft's FantaMorph 5).
.FMS  FreeMIDI Settings file (GNU FreeMIDI).
.FMT  Format file (Microsoft Visual FoxPro).
.FMX  Delphi application resource file.
.FMZ  Font file (SavedByTech Scream).
.FMZ  form-Z container file (form-Z RadioZity).
.FNT  Font files (Many variants, many applications/games).
.FOG  Fontographer font project file (Macromedia Fontographer).
.FOR  Formula Translation/Fortran programming language program/source code file.
.FORT Formula Translation/Fortran programming language program/source code file.
.FOX  FoxPro or FoxPro configuration file (Microsoft FoxPro for Windows).
.FP   FoxPro or FoxPro configuration file (Microsoft VisualFoxPro).
.FPC  FoxPro Catalog file = Similar to a dBase IV catalog (Microsoft Visual FoxPro).
.FPDOCLIB FrontPage Document Library file (Microsoft FrontPage).
.FPHOME FrontPage Homepage file (Microsoft FrontPage).
.FPHOMEOP FrontPage Homepage Open file (Microsoft FrontPage).
.FPL  Future Pinball resource Library file (Future Pinball).
.FPLIST FrontPage List file (Microsoft FrontPage).
.FPM  Future Pinball Model file (Future Pinball).
.FPNOPUB FrontPage No Publishing file (Microsoft FrontPage).
.FPOPEN FrontPage Open file (Microsoft FrontPage).
.FPQ  FoxPro updatable Query File (Microsoft Visual FoxPro 6).
.FPR  FrontPage Resource or template file (Microsoft's Office XP Frontpage).
.FPR  FruityLoops Preset file (Image-Line FruityLoops Pro).
.FPRAM Future Pinball RAM resource file (Future Pinball).
.FPRS FrontPage Resource or template file (Microsoft Office FrontPage).
.FPSURVEY FrontPage Survey file (Microsoft's FrontPage).
.FPT  Faceplate file (Liquid Audio player).
.FPT  FoxPro memo file (Microsoft FoxPro 2, Microsoft Visual FoxPro 6).
.FPT  Future Pinball Table file (Future Pinball).
.FPW  FoxPro for Windows configuration file (Microsoft's FoxPro for Windows).
.FPWEB FrontPage Website file (Microsoft FrontPage).
.FPX  FlashPix image format file (Many graphics/images applications).
.FRAG Color Fragment or color Fragmentation algorithm.
.FRAMESET Frameset file.
.FRD  Fyrad game and settings save file (Peter Sunna's Fyrad).
.FRM  Form file (Apache Tomcat).
.FRM  Merge Form file (Corel's Word Perfect Office X6).
.FRQ  File Request or File Request header (FidoNet, Binkd, and other BBS message networking relays/systems or BBS systems).
.FRT  French/Francais language file for Unreal Tournament 2003 (Digital Extremes & Epic Games UT2003).
.FRX  FoxPro Report Extension definition file (Microsoft's Visual FoxPro).
.FSFPROJ Slideshow Factory Project file (ThunderSoft Slideshow Factory 3).
.FSG  FreeCol Saved Game file (FreeCol.org's FreeCol).
.FSL  FreeStyle document/project file (Mark of the Unicorn FreeStyle).
.FSS  FreeStyle Stationary file (Mark of the Unicorn FreeStyle).
.FSS  Slideshow file (Lotus Freelance Graphics).
.FST  Freestyle Template file (Mark of the Unicorn FreeStyle).
.FT9  Freehand 9 Template file (Macromedia Freehand 9).
.FTC  FantaMorph Curve file (Abrosoft's FantaMorph 5).
.FTP  FTP site profile files (Visicom Media's AceFTP).
.FTW  Font Twister file (Neuber Font Twister).
.FV   FreshView media manager database (FreshDevices FreshView).
.FVD  FreshView media manager database (FreshDevices FreshView).
.FW2  FrameWork II spreadsheet/database file.
.FX   CorelCENTRAL Index file.
.FX2  CorelCENTRAL Index file.
.FXA  Font FX Animations file (Electric Rain Font FX).
.FXM  Font FX Materials file (Electric Rain Font FX).
.FXP  Effects Plug-in file (Twelve Tone's Cakewalk).
.FXP  Font FX Paths file (Electric Rain Font FX).
.FXP  FoxPro compiled Program file (Microsoft's Visual FoxPro).
.FXP  Steinberg VSTi effects plug-in file (Many applications/devices).
.G    MGED database file (BRL-CAD MGED).
.G41  Commodore 1541 disk drive raw GCR format disk image (Commodore emulators).
.G64  Commodore raw GCR format disk image file (Commodore emulators).
.G721 GSM audio file (Many audio applications).
.G723 GSM audio file (Many audio applications).
.G726 GSM audio file (Many audio applications).
.GAL  Gale format image file (TEMPEST's Graphics Gale).
.GAL  Gallery file (Storm Technology's EasyPhoto).
.GAL  Library gallery file (Ulead Systems' Media Studio 5 Video Editor).
.GAM  Game file (Business Game Builder).
.GBAK Get Organized Backup file (Alex Laird's Get Organized).
.GBP  GrabPic image list file (All4Soft's GrapPic 1.5).
.GBP  Grassland Backup file = ZIP archive (Grassland Invoicing).
.GC   Greeting Card document file (Sierra On-Line's Print Artist 3).
.GDL  Graph Description Language file (AbsInt Angewandte Informatik's aiSee3).
.GDL  Graph Description Language file (Many applications).
.GDL  Graphite Description Language file (SIL.ORG's Graphite Compiler).
.GDP  GameDev Project file (Benjamin Marty's Scrolling Game Development Kit).
.GED  Game Editor project file (Game-Editor.com's Game Editor Professional).
.GED  GEDCOM XML geneaology document.
.GED  Genealogical Data Communication file (Many genealogy applications).
.GEDCOM Genealogical Data Communication file (Many genealogy applications).
.GEDT Game Editor Tutorial file (Game-Editor.com's Game Editor Professional).
.GEM  GEM format image file (Digital Research's GEM Draw, Ventura Publisher, and many other graphics applications).
.GEN  General save file (NewGame Software The General).
.GEO  Geometry file (VideoScape and 3D applications).
.GETRIGHT Incomplete/Paused download file (Headlight's GetRight).
.GFI  GFI fax images (Many fax applications).
.GFP-CODEC GreenForce-Player Codec install package (GreenForce-Player).
.GFP  GreenForce-Player media file (GreenForce-Player).
.GI   RecordNow image file (Power Software's Free Any Burn).
.GIB  Jamagic 3D object container file (Clickteam Jamagic).
.GIF  Graphics Interchange File Format developed by CompuServe. (Many image applications and format variants).
.GIFF Graphics Interchange File Format developed by CompuServe (Many image applications and format variants).
.GIP  Jamagic 3D object container file (Clickteam Jamagic).
.GJM  16-bit lossless monophonic audio file (Many audio applications).
.GJS  16-bit lossless stereo audio file (Many audio applications).
.GLO  Global variables file (Business Game Builder).
.GLO  InstantText Glossary file file (Bartels Media PhraseExpress).
.GLS  giles Scene file (Leadwerks 3D World Studio).
.GLYPH Glyph file = Single character of a font file or font-making project.
.GMIS Generator Mission file (FirstPlace Software's WebPosition Gold).
.GML  Graph Modeling Language file (yWorks' yEd Graph Editor).
.GMZ  Greeting card/e-mail file (SavedByTech Scream).
.GNU  GNU General Public License file = text/documentation and rights statement (Many applications, numerous variations).
.GNUTAR GNU-TAR archive file (Smith Micro Stuffit Deluxe).
.GOO  Goo brush file (MetaTools' Kai's Power Goo).
.GP3  Guitar Pro 3 file (Guitar Pro 3).
.GP4  Guitar Pro 4 file (Guitar Pro 4).
.GRAIN Grain Surgery 2 film stock file (Visual Infinity's Grain Surgery 2).
.GRAPHML Graph Markup Language file (yWorks' yEd Graph Editor).
.GRAPHMLZ Compressed Graph Markup Language file (yWorks' yEd Graph Editor).
.GRD  Color Gradiants file (Adobe Photoshop).
.GRD  Color Gradiants file (Boris Eyrich Software Artweaver).
.GRD  Color Gradients file (Pixel Studio Pro).
.GRD  Grade/score file (Math Tutor).
.GRF  Graph file (Ivan Johansen's Graph 2.1).
.GRG  George script file (Tecsoft George, Tecsoft Video Paint/TVPaint 4).
.GROOVY Groovy programming language source code or script file.
.GRP  Program Group file (Microsoft Windows - GRPCONV.EXE).
.GRV  Groovy source code file.
.GSBA GameSave Backup Archive file (InsaneMatt's GameSave Manager 3).
.GSDU GameSave Database Update file (InsaneMatt's GameSave Manager 3).
.GSM  GSM audio (QuickTime 7.7.2).
.GTAR GNU-TAR archive file (Smith Micro Stuffit Deluxe).
.GTX  GhostTyper archive file (Bartels Media PhraseExpress).
.GVI  Google Video file.
.GWEN Gwennel document/template document file(Gwennel Doc).
.GXPA GeniuX Photo Album project file (XPro's GeniuX EFX).
.GXPE GeniuX Photo EFX image file (XPro's GeniuX EFX).
.GZ   GZip compressed file (Many applications).
.GZE  Encrypted GZIP archive file (Personal Backup).
.GZL  Go!Zilla file List file (Go!Zilla 3.x download manager).
.H    Header file (C++ programming environments/APIs).
.H2PATTERN Hydrogen drum machine pattern.
.H2SONG Hydrogen drum machine project/composition.
.HAN  Headline Animation file (MetaCreations Headline Studio).
.HAR  HTTP Archive file (Fiddler web debugger).
.HBP  Batch Processing list file (Adobe Premiere 5).
.HBS  Harbour programming language Script file (Harbour applications).
.HCD  H-Signature Cache Data file (Analinx Duplicatch).
.HCFG HoDoKu Configuration file (Bernhard Hobiger's HoDoKu).
.HCR  Half-fold Card project file (MindScape PrintMaster Gold).
.HDG  HDGraph graph/graphics file (Jean-Yves Laugel's HDGraph).
.HDP  Hard Disk/HD Project file (MAGIX Music Studio).
.HDP  HD Wave audio Project file (MAGIX Music Studio 6).
.HDR  CABinet Header file that accompanies a .CAB file of the same name (hardware/device driver installers).
.HDR  Radiance RGBE image file (LuminanceHDR).
.HDR  Song file (Bremmers Audio Design's Multitrack Studio).
.HDR  Usenet newsgroup Headers (Xnews newsreader).
.HEAD Header file (Many applications).
.HEX  Hexadecimal/binary data file = HP/Hewlett-Packard printer/scanner firmware update payload = Same as BIN.
.HF   Heightfield file (RayShade, Terrain descriptions).
.HFO  Hollywood FX Object file (Pinnacle Systems Hollywood FX).
.HFX  Hollywood FX effect file (Pinnacle Systems Hollywood FX).
.HFZ  Hollywood FX ZIP compressed archive file (Pinnacle Systems Hollywood FX).
.HGL  HP/Hewlett Packard Graphics Language file (Jasc Paint Shop Pro).
.HGT  Height map file (Shogun Total War).
.HH   HammerHead pattern file (Bram Bos' HammerHead Rhythm Station).
.HLP  Help file. The name of the help file is often the same name as the executable file for which it provides helpful information (Microsoft Windows Help).
.HMP  HoTMetaL Pro web site Project database file (SoftQuad HoTMetaL Pro).
.HOL  Holidays file (Microsoft Office XP Outlook).
.HPF  HomePage Factory link file (ICQ2000a).
.HPG  Hewlett-Packard Graphics Language plotter format image (Many graphics and modelling applications).
.HPGL Hewlett-Packard Graphics Language plotter format image (Many graphics and modelling applications).
.HPI  Hemera Picture/clip art file (Hemera's Photo Objects Sampler).
.HPJ  Help Project file (Microsoft Help Workshop).
.HPP  C++ programming language source code file.
.HPP  HoTMetaL Pro web site Project file (SoftQuad HoTMetaL Pro).
.HPU  Homepage Upper profile (TeuchiSoft Homepage Upper).
.HQX  BinHex archive file (SmithMicro's Stuffit Deluxe 2010 and other archive applications).
.HSA  ClickHelp file = HTML/Markup/Script-based (Clickteam JaMagic).
.HSOL HoDoKu format Sudoku puzzle file (Bernhard Hobiger's HoDoKu).
.HSP  Hollywood FX Spline Preset file (HollywoodFX Incorporated Hollywood FX).
.HST  Command History file (ZedTech's ZTreeWin and other command-line/CLI applications).
.HT   HyperTerminal session log files (Hilgraeve's HyperTerminal).
.HTA  Hyper-Text Application file = Browser-based application (Many browsers, HTML editors, web developer environments).
.HTB  HyperText Studio Backup project file (Olson Software HyperText Studio).
.HTC  Hyper Text database Connector file (Microsoft FrontPage).
.HTK  HTML template file (FirstPlace Software's WebPosition Gold).
.HTM  Hyper Text Markup Language file.
.HTML Hyper-Text Markup Language file (Internet browsers and many other applications).
.HTS  HyperText Studio project file (Olson Software HyperText Studio).
.HTT  HyperText Template file (Olson Software HyperText Studio).
.HTX  Database connector HTML template file (Microsoft Frontpage).
.HXX  C++ programming language source code file.
.ICB  TGA format image files = TGA file.
.ICD  IronCAD drawing format (Many CAD applications).
.ICF  Install Configuration File (Cheyenne InocuLAN 4).
.ICF  Iometer Configuration File (Iometer).
.ICL  Icon Library file (Cursor Arts' IconForge 6).
.ICL  Icon/cursor Library file (Most icon and cursor editing applications for Windows).
.ICMA InCopy Assignment file (Adobe InDesign).
.ICML InCopy story file (Adobe InDesign).
.ICN  Magic Desk Icon file (Hagen Wieshofer's Icon Edit Pro).
.ICNS Icons file = Multiple images (Many applications).
.ICO  Icon file (Hagen Wieshofer's Icon Edit Pro).
.ICO  Icon file (Microsoft Windows and many other applications).
.ICR  Icon Resource file (Hagen Wieshofer's Icon Edit Pro).
.ICS  iCalendar Calendar file (SoftMaker Office eM Client, Microsoft Outlook, and other calendar task managers).
.ID4  Infini-D 4.0 object file (Infini-D 4.0).
.IDF  Index File (Microsoft Windows).
.IDL  Interface Definition Language interface definition file (Many applications).
.IDML IDML markup file (Adobe InDesign).
.IDNL IDML asset Library file (Adobe InDesign).
.IDNS IDML snippet file (Adobe InDesign).
.IDW  Inventor Drawing file.
.IDX  Index file (WordPerfect Office QuickFinder extension).
.IDX  Resource/Library Index file = Index of a resource or library (Many applications).
.IDX  Single entry Index file (Ashton-Tate's dBase, Microsoft's FoxBASE+, Microsoft Visual FoxPro 6 and other database applications).
.IFF  Amiga OS ILBM image file (Many graphics/media applications).
.IFF  Maya IFF image file (Many graphics/animation applications).
.IFL  InstallForge Language file (InstallForge un-installed/installed applications).
.IFS  QNX File System Indexation file (QNX and environments supporting QNX).
.IG   IGES model file (IGESToolbox).
.IGES IGES model file (IGESToolbox and other 2D/3D applications. Far too many variations).
.IGN  Ignore list file (WelchWare QuickClean).
.IGS  IGES model file (IGESToolbox and other 2D/3D applications).
.IL   Icon/cursor Library file (Aha-Soft's IconUtils ArtCursors).
.IM   AIM grey scale image (Image applications).
.IM   Image file (Cincom VisualWorks SmallTalk).
.IMA  AIM grey scale image (Image applications).
.IMA  CD Image file (WinImage).
.IMA  Floppy disk Image file (Power Software's Free Any Burn).
.IMG  CloneCD Image file (Power Software's Free Any Burn).
.IMG  Disk Image file (Many disk image writer/creator/authoring applications).
.IMG  GEM Paint bitmap format Image file (GEM Paint, many other graphics applications).
.IMG  IMG format image file (Electric Image).
.IMK  InvisiMail public and RPK server Key file (InvisiMail).
.IMM  Import driver file (Macromedia Authorware 6).
.IMP  Import driver file (Macromedia Authorware 6).
.IMS  Imagestamp file (Boris Eyrich Software Artweaver).
.INC  Includes file (Many applications and variants).
.INL  C++ Builder Project file (C++Builder).
.INSTALLSTATE Install State file (Sea Star Development's Script Monitor Service).
.INT  Initialization file (Many applications).
.INTR Myst 4 Interpreter file (UbiSoft's Myst 4 Revelation).
.IOB  Imagine Object scene file (Imagine).
.IPF  Interchangeable Preservation Format file (CAPS-Project applications).
.IQP  IQUI image effect preset file (Image editors and plug-ins).
.IQS  IQUI image effect script file (Image editors and plug-ins).
.IQY  Internet Query file (Microsoft Excel).
.IR   Infra-Red device code mapping file (SlimServer).
.IRP  InfraRecorder Project file. UTF-16 encoded XML document defines project resources (InfraRecorder).
.IRP  Project file (MultimediaConvertors' MC Burner).
.ISC  Invisible Secrets (en-)Crypted file (NeoByte Solutions' Invisible Secrets).
.ISF  Pattern image files (Image editors).
.ISO  Disk image (Many applications, a number of variants).
.ISO  Disk image file (Saturn Disk Image Creator).
.ISO  DVD/BluRay disc ISO image file (Many disc authoring/imaging applications).
.ISO  ISO definition/documentation.
.ISO  ISO9660, ISO9660+UDF or UDF CD/DVD disk image file (Golden Hawk's CDRWin).
.ISS  Inno Setup Script file (Inno Installer Unpacker).
.IST  Image Styler image project file (Adobe Image Styler).
.ISZ  ISZ image file (Power Software's Free Any Burn).
.IT   Demo/Sampled music (Brain Block Interactive's Arcade Mah Jongg).
.IT   Impulse Tracker Module/Song audio file (Many tracker/audio applications).
.ITF  Image Tuner File = File paths list (Glorylogic Image Tuner).
.ITF  Interactive Theater File (Elefant Software Interactive Theater).
.ITT  Italian/Italiano language file for Unreal Tournament 2003 (Digital Extremes & Epic Games UT2003).
.IVC  InterVoice audio file.
.IVF  Indeo Video File = video file encoded with an Indeo codec. Open with any AVI-capable players.
.IWI  Infinity Ward DXT1 texture Image file (Martin Wright's DXTBmp Editor).
.IX   CorelCENTRAL Index file (Part of old Corel WordPerfect suites).
.IX2  CorelCENTRAL Index file (Part of old Corel WordPerfect suites).
.IZS  Instantz Script file = Javascript (Evrsoft's 1st Page 2000).
.J    Jamagic script source file (Clickteam JaMagic).
.J2K  LEAD proprietary JPEG2K/JPEG 2000 image format file that supports lossless JPEG imagery (A finite number of image editors/applications).
.JAR  Java format Archive container (Many applications and devices).
.JAR  Java programming language JAR application file (Many applications).
.JAV  Java programming language source code file (Many applications).
.JAVA Java programming language source code file (Many applications).
.JBF  Jasc image Browser File = images index (Jasc Paint Shop Pro).
.JBR  Jasc Brush file (Jasc Paint Shop Pro).
.JCM  Jasc CMYK color profile file (Jasc Paint Shop Pro).
.JFIF JPEG File Interchange Format image file = JPEG image (Many applications).
.JGD  Jasc color Gradient file (Jasc Paint Shop Pro).
.JMI  NetImmersive/Gamebryo Model file (NifTools NifSkope).
.JOB  Job file (Cheyenne InocuLAN 4).
.JOB  Job Order file (Padus DiskJuggler.NET's PFCNET command line utility).
.JOT  Jot+/JotPlus format document (King Stairs' Jot+/JotPlus Notes).
.JPE  InnoculateIT Windows system file backup file (Computer Associates' InnoculateIT).
.JPE  Joint Photographics Expert Group file interchange format image file = A holdover/tradition from MS-DOS/DOS systems whose extensions having a 3 character limit truncated the last letter of JPEG (Many applications).
.JPEG Joint Photographics Expert Group file interchange format image file (Many applications).
.JPG  Joint Photographics Expert Group file interchange format image file (Many applications).
.JRC  Jamagic resource file (Clickteam JaMagic).
.JS   JavaScript scripting language file (Many applications, especially web document-driven applications).
.JS   JavaScript scripting language file (Ali Almossawi's/CyberiaPC's AAScripter).
.JSL  J# language source code or source code snippet file (Microsoft VisualJ# "JSharp").
.JSON JavaScript Object Notation file (Many applications).
.JSP  Java Server Page source code file (Java applications).
.JWW  Jww Drawing file (LibreCAD).
.K3D  K-3D 3D project file (Timothy M Shead's K-3D 0.8).
.K3G  Video file (Mobile phones).
.KAOS KAOS Diagram file (KAOS).
.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).
.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).
.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  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 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).
.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).
.MYD  MyDefrag script file (Jeroen Kessels' MyDefrag).
.MYD  MySQL MYD file (Many applications).
.MYD  MySQL MYI file (Many applications).
.NAB  Nero Audiobook compilation file (Nero Burning ROM/Nero Express).
.NAROXML NaroCAD XML document file (NaroCAD).
.NBA  Nero BackItUp Archive file (Nero Burning ROM/Nero Express).
.NBI  Nero BackItUp Information file (Nero Burning ROM/Nero Express).
.NBT  Nero BackItUp Template file (Nero Burning ROM/Nero Express).
.NC   (IGESToolbox).
.NC_  Nero Splitted File (Nero Burning ROM/Nero Express).
.NCD  Name Cache Data file (Analinx Duplicatch).
.NCD  Nero CD-ROM Cover Designer project file (Nero Burning ROM/Nero Express).
.NCD  NTI CD-Maker image file (Power Software's Free Any Burn).
.NCO  Nero BackItUp Compressed archive file (Nero Burning ROM/Nero Express).
.NCW  Nero Cover Wizard file (Nero Burning ROM/Nero Express).
.NDA  Nero BackItUp Drive Archive file (Nero Burning ROM/Nero Express).
.NDF  Net Draft document file (SPIRITware Net NOTES).
.NDO  Nendo image file.
.NEF  Nero BackItUp Encrypted file (Nero Burning ROM/Nero Express).
.NEF  Nikon Electronic Format image file = primarily RAW digital camera photos (Nikon cameras and many image applications, numerous variants).
.NEOMAP NeoTrace IP address Map file (NeoWorx' NeoTrace 2.1).
.NET  Net NOTES document file (SPIRITware Net NOTES).
.NET  PCB Net list file (Matt Pyne's TinyCAD and other applications, many variations).
.NEW  Empty file.
.NEW  Temporary file (Krita).
.NEWSRC Usenet newsgroups and header indices (Xnews).
.NFF  Neutral File Format file (Eric Haines' SPD ray tracing program utility and other applications).
.NFF  Neutral File Format file. This is not the same as Eric Haines' NFF files (World Toolkit).
.NFT  NetObjects Fusion Template file (Corel Website Creator X6).
.NHF  Nero HFS CD compilation (Nero Burning ROM/Nero Express).
.NHV  Nero HD-BURN Video compilation (Nero Burning ROM/Nero Express).
.NID  Name cache Index Data file (Analinx Duplicatch).
.NIF  NetImmersive/Gamebryo model File (NifTools NifSkope).
.NIFCACHE NetImmersive/Gamebryo model File (NifTools NifSkope).
.NIL  Icon Library file (Cursor Arts' IconForge 6).
.NIL  Icon/cursor Library file (Aha-Soft's IconUtils ArtCursors).
.NJI  Nero BackItUp Job Information file (Nero Burning ROM/Nero Express).
.NJT  Nero BackItUp Job Template file (Nero Burning ROM/Nero Express).
.NKP  NoteKeeper Project file (Alex Paterson's NoteKeeper).
.NMD  Nero miniDVD compilation file (Nero Burning ROM/Nero Express).
.NMZ  Animation file (SavedByTech Scream).
.NOD  NetObjects Fusion Document file (Corel Website Creator X6).
.NOT  Note project file (MindScape PrintMaster).
.NR3  Nero CD-ROM MP3 audio compilation (Nero Burning ROM/Nero Express).
.NR4  Nero CR-ROM AAC audio compilation (Nero Burning ROM/Nero Express).
.NRA  Nero Audio CD compilation (Nero Burning ROM/Nero Express).
.NRB  Nero Bootable CD-ROM compilation (Nero Burning ROM/Nero Express).
.NRC  Nero UDF/ISO CD compilation file (Nero Burning ROM/Nero Express).
.NRD  Nero DVD video compilation file (Nero Burning ROM/Nero Express).
.NRE  Nero CD-EXTRA compilation file (Nero Burning ROM/Nero Express).
.NRG  Nero compact disc image file (Nero Burning ROM/Nero Express).
.NRH  Nero Hybrid compact disc compilation (Nero Burning ROM/Nero Express).
.NRI  Nero ISO compact disc compilation (Nero Burning ROM/Nero Express).
.NRW  Nikon RAW image file (Nikon cameras and many image applications).
.NRZ  High scores file (Drazen's Logyx Pack).
.NSI  NSIS file.
.NSV  NullSoft Video file = Nullsoft = Developer of the popular WinAmp media player.
.NSX  NetSwitcher Extension file (NetSwitcher 2).
.NTF  MediaFACE project file (Neato MediaFACE II).
.NTT  MediaFACE project template file (Neato MediaFACE II).
.NTX  yEnc-encoded file (SmithMicro's Stuffit Deluxe and other archive applications).
.NVL  Navaho 2.1 Lock file (Navaho ZipSafe).
.NWS  News/Usenet News file (Microsoft Outlook, Microsoft Outlook Express).
.NWS  Newsletter project file (MindScape PrintMaster).
.O    Object file (FreeBasic developer environments and editors).
.O    Object file (Many applications).
.O    Output file (Many applications).
.OB2  Oberon file.
.OBD  Office Binder file (Microsoft Office).
.OBJ  WaveFront Object file.
.OBT  CM-Projekt file.
.OBT  Office Binder Template file (Microsoft Office).
.OBZ  Office Binder Wizard file (Microsoft Office).
.OCT  Octave script file (Michael Margraf's QUCS/Quite Universal Circuit Simulator).
.ODB  Open Document format data Base file (Many applications).
.ODB  Open Document format Database file.
.ODC  Microsoft Office Data Connection file (Microsoft Office XP Professional).
.ODF  Hybrid PDF/ODF document = Standard PDF file containing an ODF document (OpenOffice-based applications with PDF support).
.ODF  Open Document format Formula file (Many applications).
.ODG  Open Document format Drawing (Many applications).
.ODG  Open Document format Graphics vector image (OpenOffice, Libre Office, etc.).
.ODM  Open Document format Master document (Office applications).
.ODP  Open Document format Presentation template file (Many applications).
.ODS  Open Document format Spreadsheet file (Many applications).
.ODT  Open Document format Text file (Many applications).
.OFL  Open Font License file = Text.
.OFR  OptimFROG format audio file.
.OFS  OptimFROG format audio file.
.OFT  Outlook e-mail message File Template file (Microsoft Office XP Outlook).
.OFX  OpenFX Animator format file (OpenFX).
.OGA  Ogg Vorbis audio Album file (Many audio applications).
.OGG  Ogg Vorbis Audio file (Many audio applications).
.OGV  Ogg Vorbis Video file (Many audio applications).
.OMF  Open Media Framework video file (Adobe Systems' Premiere, Adobe Systems' Audition).
.OMS  Open Music System file (Many audio/MIDI applications).
.ONE  Onespace page file (Enfish Onespace Personal).
.ONS  High score file (Lasse Rautiainen's Golf).
.OPML Open Markup Language file = XML based markup language (Many applications).
.OPS  Office Profile Settings file (Microsoft Office Profile Settings Wizard).
.OPZ  Outback Plus mail archive = OutLook mail backup (AJ Systems' Outback Plus).
.OQY  OLAP Query file (Microsoft Excel).
.OR2 .OR5 Lotus Organizer files. 2=v2 3=v97 4=4.1 and v97GS 5=v5 (Lotus Development's Lotus Organizer).
.ORA  OpenRaster Archiving image file (Martin Renold's MyPaint and many other graphic image applications).
.ORC  CSound orchestra file (Algorithmic composition applications that employ the CSoundAC API, CSoundQt).
.ORF  Olympus RAW Format image file (Olympus cameras, many image applications, many variants).
.ORG  Lotus Organizer files (Lotus Development's Lotus Organizer 1).
.ORK  OpenRocket design project file (OpenRocket).
.ORP  Orangator Presets file (Agent Orange and Tangerine's Orangator).
.OTF  OpenType Font files (Many applications).
.OTH  HTML document template.
.OTL  Outline file (Fookes Holdings' NoteTab and other text editors).
.OTO  Hugin PanoTools.
.OTT  Open Document format Text Template file (Calligra Words and many other word processing applications).
.OUT  Bundler Output file (Visual Computing Lab - ISTI - CNR's MeshLab).
.OUT  Output placeholder file = An empty temporary file which is renamed to a file or folder before content is added/extracted into it (Smith Micro's Stuffit Deluxe and Stuffit Expander).
.OUTLINE Letter Outline file (Neuber Font Twister).
.OVL  Overlay file (Many applications and variants).
.OXT  Open Extension file (LibreOffice, OpenOffice and other Office applications/suites).
.OZ   Bitmap character table graphics file (Oz & Kenichi's Tower of the Sorcerer).
.P    Prolog programming language file.
.P01  Gear image file (Power Software's Free Any Burn).
.PAK  Fox Pack file = compressed container file (FoxPro).
.PAK  Package file = archive (Many games and formats).
.PAL  Color palette (LinCity-NG).
.PAL  Color Palette file (Many graphics applications and format variations).
.PAL  Palette file (C Jain's Mountain 3D).
.PAL  Palette file (Equilibrium's DeBabelizer 5).
.PAL  Palette file (Hagen Wieshofer's Icon Edit Pro).
.PAL  Palette file (Jasc Paint Shop Pro).
.PAL  Palette file (Pixel Studio Pro).
.PAL  PhraseExpress words file (Bartels Media PhraseExpress).
.PAL  RIFF Palette file (Ulead Video Paint).
.PAP  Paper file (Boris Eyrich Software Artweaver).
.PAQ  PAQ archive file (Many variants and applications).
.PAQ8O PAQ8O archive file = brute force compression algorithms (PeaZip).
.PART Partial file (eMule, GoZilla, and many other file transferring/writing/sharing applications).
.PAS  Pascal/Delphi programming language source code file.
.PAT  Hatch Pattern image file (CorelCAD).
.PAT  Pattern image file (CorelDRAW).
.PAT  Pattern image file (Jasc Paint Shop Pro).
.PB   PureBasic code (PureBasic applications).
.PBA  Pixel Animated Brush file (Pixel Studio Pro).
.PBD  PhotoDeluxe Business Edition Document file (Adobe's PhotoDeluxe Business Edition).
.PBI  PureBasic Includes file (PureBasic applications).
.PBK  Phonebook file (Windows Remote Access Services/RAS).
.PBL  Premiere Batch capture List file (Adobe Premiere 5).
.PBM  Portable Bitmap image file (Many applications).
.PBU  Personal Backup file (Personal Backup).
.PBV  Paint Brush file (Boris Eyrich Software Artweaver).
.PC   Postcard document file (Sierra On-Line's Print Artist 3).
.PCA  Perfect Clarity Audio file (Sonic Foundry Sound Forge).
.PCD  Kodak CMS Photo CD images (Multiple sizes).
.PCK  PL/SQL stored procedures Package file (Oracle's PL/SQL).
.PCL  Compiled Parcel format file (Cincom VisualWorks SmallTalk).
.PCM  Raw PCM audio file (Many audio applications).
.PCPATCH NetImmersive/Gamebryo model File (NifTools NifSkope).
.PCR  Postcard project file (MindScape PrintMaster Publishing Suite).
.PCS  Painter Color Set file = Palette (MetaCreations Painter).
.PCX  Fax file (ElectraSoft 32bit Fax 9).
.PDB  Microsoft C/C++ Database file (Many applications).
.PDD  PhotoDeluxe Document file (Adobe PhotoDeluxe and Photoshop).
.PDF  Portable Document Format file developed by and for Adobe Acrobat (Many applications).
.PDI  InstantCopy Image file (Power Software's Free Any Burn).
.PDN  Paint.Net image file (Circular & Fabien Wang's LazPaint 4).
.PDN  Portable Draughts Notation file containing one or multiple games (Harm Jetten's DAM and other Draughts games).
.PDO  Paradox table file (Paradox 3 and 4).
.PDQ  Flowchart file (Flowcharting PDQ).
.PE3  PhotoImpact Explorer 3 thumbnail image cache file (PhotoImpact Explorer).
.PEF  Pentax Electronic Format RAW image file. (Pentax digital cameras, many variants).
.PEXSQL PhraseExpress SQL database file (Bartels Media PhraseExpress).
.PF   Device colorspace Profile (Many applications).
.PFB  Prefab file (Leadwerks 3D World Studio).
.PFB  Printer Font Binary file = Adobe Type 1 font file (Many applications).
.PFC  PerfectFit Component file (Corel WordPerfect Office Suite).
.PFF  Premiere Filter Factory settings file (Adobe Premiere 5).
.PFM  Printer Font Metrics file (Many applications).
.PFR  Paint Shop Frame file (Jasc Paint Shop Pro).
.PFS  PFS stream file (LuminanceHDR).
.PFX  Personal Information Exchange file (Microsoft Windows operating systems).
.PFX  Premiere Effects/Transition file (Adobe Premiere 5).
.PFX  Preset OpenFX model file (OpenFX).
.PG4  Page template file = ZIP archive containing XML, PNG, and WAV files (Indigo Rose's AutoPlay Media Studio 4).
.PGE  EzyPage project file (EzyWare's EzyPage).
.PGM  Portable Grayscale Map image file (Many applications).
.PGP  Pretty Good Privacy encrypted file (Pretty Good Privacy).
.PHD  Photodex file mirror file = index (Photodex' CompuPic Express).
.PHP  PHP: Hypertext Preprocessor markup file (Many server applications and editors).
.PHP3 PHP 3 file (Crimson Editor, Norio Nakatani's Sakura Editor).
.PHP3 PHP 3 markup  file (Many server applications and editors).
.PHP4 PHP 4 file (Crimson Editor).
.PHP4 PHP 4 markup  file (Many server applications and editors).
.PHT  Photo album file (SSuite Office EZPhoto Album).
.PIC  Autodesk image file.
.PIC  Lotus PIC picture format image file (Many Office suites and graphics applications).
.PIC  Pegasus PIC image file = Pegasus JPEG (Many graphics applications).
.PIC  Radiance RGBE picture file (LuminanceHDR).
.PICT Picture format of the Macintosh OS. Many image processing applications import them.
.PIMX XML format Package Installation Manager file (Adobe Systems' Audition).
.PIP  Settings file (Microsoft Office XP Professional).
.PIX  Alias PIX format image file (Many applications).
.PJT  Project file (Microsoft Visual FoxPro 6).
.PJX  Project file (Microsoft Visual FoxPro 6).
.PK3  PAK 3 Package file = archive (Electronic Arts' Medal of Honor Pacific Assault, Unvanquished, and many other games/game developers).
.PKF  Temporary file (Diamond Cut Millenium).
.PKZ  Phil Katz ZIP archive file = PK is the "code-borrowing/theft" developer of the ZIP format archive (PKWare's PKZIP and other applications).
.PL   Markup that references Perl scripts (Few applications).
.PL   Perl language script file (Many applications).
.PLA  Player file (Business Game Builder).
.PLB  FoxPro 2.0 Library file (FoxPro 2.0).
.PLB  Premiere Library file (Adobe Premiere 5).
.PLG  Plug-in file (Boris Eyrich Software Artweaver).
.PLIST Preferences List file (Apple QuickTime Player).
.PLIST Property List file.
.PLR  NOX Player save file (Westwood Studio's NOX).
.PLS  Playlist file (Many audio players).
.PLT  HPGL Plotter file = Hewlett Packard/HP Graphics Language format.
.PLT  Palm Pilot image = Hewlett-Packard Graphics Language format image.
.PLT  Plot graph file (GnuPlot).
.PLT  Template/Boilerplate - precomposed document requiring marginal edits and/or automated text insertions/replacements of text or fields in order to form a completed, exportable document.
.PLUGINSPEC Plug-in specification file (Digia Qt Creator).
.PLY  Playlist file (Willow Anvil Studio 2012 and many other audio applications).
.PM   Pegasus Mail configuration file (David Harris' Pegasus Mail).
.PM   Perl Module/source code file (Many applications).
.PMD  Pegasus Mail Dictionary file (David Harris' Pegasus Mail).
.PMD  PlanMaker spreadsheet Document file (SoftMaker Office PlanMaker).
.PMO  PrintMaster Object file (MindScape PrintMaster Publishing Suite).
.PMR  PhotoModeller project file (PhotoModeller/PhotoModeller Lite).
.PMT  Premiere Motion settings or Mesh Warp filter settings file (Adobe Premiere 5).
.PMV  PlanMaker spreadsheet Template file (SoftMaker Office PlanMaker).
.PNID Postit Note description file = Text content (PNotes).
.PNOTE Postit Note file (PNotes).
.PNPTC PnP Terrain Creator project file (Team PnP's PnP Terrain Creator).
.PNQ  Plug-in file (ICQ2000a).
.PNT  MacPaint image format file (MacPaint and many image applications).
.PNTG MacPaint image format file (MacPaint and many image applications).
.POD  Perl language POD file.
.POLICY Java Policy file (Many applications).
.POT  PowerPoint Presentation design Template file (Microsoft PowerPoint and many other Office suites).
.POTHTML PowerPoint HTML Presentation design Template file (Microsoft PowerPoint).
.POTM PowerPoint Macro-enabled document Template file (Microsoft Office PowerPoint).
.POTX PowerPoint Presentation design XML format Template file (Microsoft Office PowerPoint).
.POV  POV ray format image file (POV is a free ray-tracing package).
.PP   Pre-parsed data file.
.PP4  Picture Publisher version 4 image file (Micrografx Picture Publisher version 4).
.PP5  Picture Publisher version 5 image file (Micrografx Picture Publisher version 5).
.PPA  PowerPoint Add-in file (Microsoft PowerPoint).
.PPD  Postscript Printer Description files = machine-readable text used by printing facilities to render postscript documents.
.PPF  Picture Publisher Format image file (Micrografx Picture Publisher).
.PPI  Passport initialization file (Microsoft Passport Configuration Utility).
.PPJ  Premiere Project file (Adobe Premiere 5).
.PPK  PuTTY Private Key file = RSA/DSA digital signature (Simon Tatham's PuTTY Authenticaion Agent and PuTTYgen).
.PPM  Portable Pixel Map image file (Many applications).
.PPP  Power Producer Project file (CyberLink Power Producer).
.PPR  PaintStar Project file (PaintStar).
.PPS  PowerPoint Show file (Many Office suites).
.PPS  PowerPoint Slide show file (Microsoft PowerPoint).
.PPSM PowerPoint Macro-enabled Slideshow file (Microsoft Office's PowerPoint).
.PPSX PowerPoint Presentation Slideshow file (Microsoft Office's PowerPoint).
.PPSX PowerPoint Show file (Many Office suites).
.PPT  PowerPoint Presentation file (Many Office suites, many variants).
.PPTH PowerPoint HTML document file (Office applications).
.PPTHTML PowerPoint HTML document file (Microsoft PowerPoint).
.PPTM PowerPoint Presentation Macro-enabled file (Microsoft Office).
.PPTX PowerPoint Presentation open-XML format (Microsoft Office).
.PQG  PowerQuest Graphic file = Bitmap image (PowerQuest Partition Magic).
.PQW  Presentations QuickFile runtime file (Corel Word Perfect Office X6).
.PRAPIC Praat Picture file (Paul Boersma's and David Weenink's Praat).
.PRC  Palm Resource file (Palm operating system).
.PRD  Presentations Document file (SoftMaker Office Presentations).
.PRD  Presentations Template file (SoftMaker Office Presentations).
.PRE  ArtSet Pre file (Pixarra TwistedBrush Pro).
.PREF Preference subset file (Björn Gustavsson's Wings 3D).
.PRF  PICS Rules File (Microsoft Windows - Content Advisor).
.PRF  Preferences file (eMagic SoundDiver).
.PRF  Premiere Preferences file (Adobe Premiere 5).
.PRF  Profile settings file (Microsoft Outlook).
.PRF  Project Features file (Digia Qt Creator).
.PRG  Harbour programming language Program file (Harbour applications).
.PRG  Program file (Willow Anvil Studio 2012).
.PRI  Qt Project Includes file (Digia Qt Creator).
.PRJ  Project file (Axogon Composer).
.PRJ  Project file (Daniel Taverney's Win2Web 2).
.PRJ  Project file (Many applications and variations).
.PRJ  Project file (XlineSoft's Database to HTML Express 2.2).
.PRM  Premiere plug-in file (Adobe Premiere 5).
.PRN  Fixed-width document/printer file (Various programs).
.PRN  Printer output file (Various programs).
.PRO  Process file (Business Game Builder).
.PRO  Profile file (Many applications).
.PRO  Project file (Lorenz Graf's HTMLtool).
.PRO  Project file (Many applications).
.PROGRAM Program file = program source code or script.
.PROLOG Prolog program or source code file.
.PRP  Pocket Radio Player radio station file = ZIP compressed archive (Stefan Sarbok's Pocket Radio Player).
.PRP  User prep file (Macromedia Freehand 7).
.PRS  Harvard Graphics format image (Harvard Graphics).
.PRS  Project Settings file (Adobe Premiere 5).
.PRS  Presentations Show file (SoftMaker Office Presentations).
.PRS  Preset file (Sonic Syndicate Orion).
.PRT  Presentations Template file (Corel Office).
.PRT  Print or Printer output file = a file whose content is suitable for direct output to printer devices or printer output management facilities (Many applications).
.PRV  Priviledge file (Preview Systems' Vbox Builder 4).
.PRX  Windows media Profile file (AIST MoviePack/MovieDV/MovieXone).
.PS   Adobe PostScript format file = a file that describes a printed image which requires an interpreter, such a Ghostscript, or an interpreting device, such as a PostScript capable printer, in order to print the described image (Many applications and devices, many format variations).
.PS   Paint Shop resource file (Jasc Paint Shop Pro).
.PS00 .PS09999 Puran Split file (Puran Splitter).
.PS3  Encapsulated PostScript vector based drawing (Many variants, many programs).
.PSAFE3 Password Safe database file (Password Safe v3).
.PSB  Psycle tracker Pattern file (Psycle).
.PSD  Photoshop Document format. This is the native project/image save format of Adobe's Photoshop. It enjoys significant support in third party applications, including some competitor products, though most do not recognize or handle all PSD file content.
.PSF  Photo Studio File (Arcsoft's Photo Studio 2000).
.PSP  Adobe Photoshop Preferences file (Adobe Photoshop).
.PSP  Paint Shop Pro format image file. The native image format of Paint Shop, it is supported by some third party image editors and graphics applications (Jasc Paint Shop Pro, now owned and developed by Corel Corporation).
.PSQ  Premiere Sequence file (Adobe Premiere 5).
.PSS  PostScript printer Stub file (Many printing/font applications).
.PST  Personal folders (Microsoft OutLook/OutLook Express).
.PST  Plug-In Settings file (MAGIX Music Studio 6).
.PST  SmallTalk source code Parcel file (Cincom VisualWorks SmallTalk).
.PSV  Psycle tracker display presets file (Psycle).
.PSW  Pixel Swatch file (Pixel Studio Pro).
.PSW  Pocket Word format document file (Pocket Word, SoftMaker Office TextMaker and other word processor applications).
.PSY  Psycle tracker song/sample/instrument file (Psycle).
.PTB  Panorama Tools batch panorama/stitcher script (Panorama Tools, Hugin, etc.).
.PTC  Patch file = audio/loop (Audio applications).
.PTL  Premiere Title file (Adobe Premiere 5).
.PTM  Pixel Template file (Pixel Studio Pro).
.PTO  Panorama Tools/PanoTools panorama/stitch project file (Hugin).
.PTP  PanoTools file (Hugin PanoTools).
.PTS  Panorama Tools/PanoTools script file (PanoTools, Hugin, etc.).
.PTS  Presets file (Nothing Else Matters' vTuner).
.PTX  Pattern file (Pixel Studio Pro).
.PTX  Presets file (Jasc Paint Shop Pro).
.PVK  Private/Privacy Key file (Microsoft Windows operating systems).
.PWZ  PowerPoint Wizard file (Microsoft PowerPoint).
.PX   Pixel image file (Pixel Studio Pro).
.PX3  PhraseExpress Phrases file (Bartels Media PhraseExpress).
.PXI  PlexTools Image file (Power Software's Free Any Burn).
.PXP  PhraseExpress Phrases file (Bartels Media PhraseExpress).
.PXR  Pixar image file (Adobe Photoshop and many other graphics applications).
.PY   Python programming language application or script file (Many variants, many applications).
.PY   Python script file (Timothy M Shead's K-3D 0.8).
.PYC  Python cache file (Stichting Blender Foundation's Blender).
.PYD  Python file (Many variants and applications).
.PYO  Python file (Many variants and applications).
.PYPROJ Python Project file (sharpdevelop.net's JSharp Develop 4).
.PYW  Python file (Many variants and applications).
.Q3D  QuickDraw 3D file (Apple Quickdraw 3D and 3D editors/viewers).
.QB   QuickBurn CD layout file (RMBSoft QuickBurn).
.QBE  Relational Query By Example query file (Microsoft FoxPro).
.QCD  Quark CopyDesk Document file (Quark CopyDesk).
.QCL  Quark Color Library file = XML markup (Quark CopyDesk and other Quark products).
.QCP  QCP audio (QuickTime 7.7.2).
.QCP  Quark CopyDesk Page picture file (Quark CopyDesk).
.QCT  Quark CopyDesk Template file (Quark CopyDesk).
.QDR  Q-Dir saved system state file (Q-Dir).
.QDT  QuarkXPress auxillary Dictionary file (QuarkXPress Passport).
.QDV  QDV format image file (Random Dot Software).
.QFS  QNX File System image file (QNX and environments supporting QNX).
.QHT  QuickTime HTML markup file (QuickTime 7.7.2).
.QHTM QuickTime HTML markup file (QuickTime 7.7.2).
.QIF  Quicken Interchange Format file (Many money-management/tax applications).
.QML  QML language project file.
.QMLTYPES QML Type description file (Digia Qt Creator).
.QP   QuickPAR task file (QuickPAR).
.QPC  QuickPAR Cache file (QuickPAR).
.QPR  FoxPro SQL Query or Query Program file (Microsoft Visual FoxPro 6).
.QPW  Quattro Pro X6 notebook file (Corel Word Perfect Office X6).
.QRC  Qt Resource file (Digia Qt Creator).
.QRC  Quark Required Components resource file (QuarkXPress and other Quark products).
.QT   QuickTime movie (Apple's QuickTime Player).
.QTI  QuickTime image (QuickTime 7.7.2).
.QTIF QuickTime image (QuickTime 7.7.2).
.QTL  QuickTime movie (QuickTime 7.7.2).
.QTM  QuickTime Markup language file (Apple's QuickTime Player).
.QTML QuickTime Markup Language file (Apple's QuickTime Player).
.QTN  Quarantined file - malware or suspected malware (Malware/Anti-virus applications).
.QTP  QuickTime Preferences file (Apple QuickTime Player).
.QTR  QuickTime Resource file (Apple QuickTime Player).
.QTVR QuickTime Virtual Rendering file = 3D environment rendered in 2D video viewed with one eye closed (Apple's QuickTime Player).
.QUCS QUCS package file (Michael Margraf's QUCS/Quite Universal Circuit Simulator).
.QUE  Queue file (GlobalScape CuteFTP).
.QVM  QT Virtual Machine (QT applications).
.QWD  QuarkXPress Web Document file (QuarkXPress Passport).
.QWT  QuarkXPress Web Template file (QuarkXPress Passport).
.QXB  Quark CopyDesk Book file (Quark CopyDesk).
.QXD  QuarkXPress Document file (QuarkXpress).
.QXL  QuarkXPress Library file (QuarkXPress).
.QXT  QuarkXPress Template file (QuarkXpress).
.R00 .R29 Multi-volume RAR archive file (Roshal's WinRAR and many archiver applications).
.RA   RealAudio audio file (Real Networks' RealPlayer 7).
.RAD  Rapid Application Development FreeBASIC template file (KetilO's FbEdit FreeBASIC Editor).
.RAF  Fuji RAW Format image file (Fuji cameras, many image applications, many variants).
.RAM  RealAudio playlist file (Audio/video editors and players).
.RAP  RAM Project file (MAGIX Music Studio).
.RAP  Roland Audio Producer sample/loop file (Audio composers/samplers).
.RAR  RAR archive file (Roshal's WinRAR and many archiver applications, a number of variants).
.RAS  Sun Microsystems Raster image format (Many applications).
.RAT  Ratings file = Sites/Content (Microsoft Windows - Content Advisor).
.RAW  Raw binary image (Many applications).
.RB   Ruby source code or script (Many applications).
.RB1 .RB4 StarBase database file (Sun's StarOffice 5.1).
.RBK  Desktop and shortcut backups (Desktop Maestro).
.RBK  Redbook compact disc audio file (Many devices and applications).
.RBM  Registry Bookmark file (Greatis' RegRun Security Suite 3).
.RBS  ReBirth RB-338 Song file (Audio applications).
.RC   Resource or Resource script file (Many applications and operating systems).
.RCAL RGS Agenda Calender file (RGS-Cardmaster).
.RCY  ReCycle audio sample loop editor (ReCycle, Dr. Rex, and other editors/players).
.RD3  Ray Dream Studio version 3 object (MetaCreations Ray Dream Studio).
.RD4  Ray Dream Studio version 4 object (MetaCreations Ray Dream Studio).
.RD5  Ray Dream Studio version 5 object (MetaCreations Ray Dream Studio).
.RDB  Rigid Disk Block partition table file (Amiga operating system).
.RDD  Ray Dream Studio version 5 document (MetaCreations Ray Dream Studio).
.RDF  Scrapbook archive (BauerApps RightNote).
.RDS  Ray Dream Studio project/object file (MetaCreations Ray Dream Studio and other 3D editors).
.RDW  Real-DRAW project file (MediaChance Real-DRAW).
.RDX  Rolodex database file.
.RE   RE file (IGESToolbox).
.REG  Product registration instructions/information file = text file (Many application distributions).
.REG  Registry file = A text file that defines data stored within the Windows registry or which will be written to the registry if the file is executed/merged with the Windows registry (Windows operating systems).
.REGISTRATION Product registration information = text or readable document file that accompanies software installers/distributions (Many applications).
.REL  Relative file = A Commodore DOS file comprising two distinct files referenced in a single Commodore DOS file directory entry where one file chain of tracks and sectors (side sectors) records the tracks and sectors used by the other file chain - the data file (Many Commodore computer emulator applications, especially database applications).
.RELS Relationships file = XML markup (DOCX, many documents).
.REP  Lotus Reporter layout file (Lotus Development's Lotus Organizer).
.RES  Resource file (Many applications and variations).
.RES  Resource file (Steam platform game engine).
.RESOURCES Binary resource file (sharpdevelop.net's JSharp Develop 4).
.RESX Resource file (sharpdevelop.net's JSharp Develop 4).
.RESX XML based resource file (Many applications).
.REX  REX audio sample loops file (Many loop players and editors).
.REX  Restructured Extended Executor/REXX programming language program or script file (Open Object Rexx).
.REXG Restructured Extended Executor/REXX programming language GUI program file (Open Object Rexx).
.REXP Restructured Extended Executor/REXX programming language Pausing program file (Open Object Rexx).
.RF   Flash/Shockwave file (Real Networks' RealPlayer 7).
.RGB  SGI truecolor image file (Many image applications).
.RGBA SGI truecolor image with alpha channel file (Many image applications).
.RGBE RGBE image file = 3 bytes RGB data and 1 byte shared exponent for greater bit depth.
.RIF  Image File (Corel Painter 11, Corel Paint It!).
.RJS  RealSystem skin package file (Real Networks' RealPlayer 7).
.RJS  Ruby file.
.RKT  Rocket design project (RockSim).
.RLE  Run Length Encoded bitmap images (Many applications).
.RLS  RadLight Skin file (RadLight 3.x).
.RM   RealMedia audio file (RealMedia player).
.RM   Removals file (Cincom VisualWorks SmallTalk).
.RMBAK Registry Mechanic registry compaction Backup file (PCTools Registry Mechanic).
.RMF  Rights Management File (Adobe Acrobat/Acrobat Reader).
.RMI  MIDI file (Many applications).
.RMP  RealJukebox Music Package file (Real Networks' RealPlayer 7).
.RMX  RealSystem secure Media clip (Real Networks' RealPlayer 7).
.RNA  Nero Audio CD compilation file (Nero Burning ROM/Nero Express).
.RND  Random seed file (WinSCP).
.RNT  RightNote notebook file (BauerApps RightNote).
.RNX  RealPlayer file (Real Networks' RealPlayer 7).
.ROV  Rover file (S&H Computer's NewsRover).
.RP   RealPix picture file (Real Networks' RealPlayer 7).
.RP   RP file (Axure RP Pro).
.RP0  RPK authorization Fail file (InvisiMail).
.RP1  RPK authorization OK file (InvisiMail).
.RPA  Alias/Wavefront image files (Image editors).
.RPD  RapidFile file (RapidFile).
.RPF  Alias/Wavefront image files (Image editors).
.RPK  InvisiMail public and RPK server Key file (InvisiMail).
.RPLIB RP Library file (Axure RP Pro).
.RPPRJ RP Project file (Axure RP Pro).
.RPS  Reason Published Song file (Propellerhead's Reason).
.RPT  TCM Report file (Apt Systems Total Contact Management).
.RPT  TCM Template file (Apt Systems Total Contact Management).
.RR2  RegRun 2 startup profile file (Greatis' RegRun Security Suite 3).
.RRR  Registry Mechanic registry compaction temporary file (PCTools Registry Mechanic).
.RS   Red Storm image format (ACD Systems' ACDSee).
.RSA  Audio filter file (Ulead Systems Media Studio 5 Video Editor).
.RSA  RSA digital signature authentication file  = public or private key (Many applications).
.RSC  Clone option file (Ulead Video Paint).
.RSE  RockSim Engine file (RockSim).
.RSEX Microsoft ResX Resource in XML format file.
.RSF  Video Filter option file (Ulead Video Paint).
.RSJ  Restore Job file (Personal Backup).
.RSM  Macro option file (Ulead Video Paint).
.RSML RealSystem Markup Language file (Real Networks' RealPlayer 7).
.RSN  Reason project or project template file (Propellerhead's Reason).
.RSP  Paint option file (Ulead Video Paint).
.RSR  Poser file (Poser 4).
.RSR  Retouch option file (Ulead Video Paint).
.RST  ReStructured Text file (ActiveState's Komodo Edit).
.RT   RealText document file (Real Networks' RealPlayer 7).
.RTC  Rich Text Compressed format document = Compressed RTF file (Many word processors).
.RTF  Rich Text File document (Many word processors).
.RTF  Rich Text File (Shellfish's NotePro 1.3).
.RTFD Rich Text Format Directory file (TextEdit, Bean).
.RTL  Raster Transfer Language image file (An image format for plotter printers).
.RTS  Real Time Streaming Protocol (QuickTime 7.7.2).
.RTSP Real Time Streaming Protocol (QuickTime 7.7.2).
.RULESET Ruleset file (FreeCiv).
.RV   RealVideo file (Real Networks' RealPlayer 7).
.RVF  RichView File = Rich text document (BauerApps RightNote).
.RWX  Renderware file (Criterion's Renderware).
.RX   Restructured Extended Executor/REXX programming language program file (Open Object Rexx, Regina Rexx and other applications).
.RX2  REX2 audio sample loops file (Many loop players and editors).
.RXML Ruby XML file.
.S    Source code file (Many applications).
.S    Temporary/Backup/Save file.
.S37  Modem installation files (Rockwell 56KFlex Modemwave/Genius series).
.S3D  Simply 3D format image file (Micrografx Simply 3D).
.S3M  ScreamTracker Module audio file (Many audio/tracker applications).
.SAF  Safe file (Encryption and database applications).
.SAF  Safe file (InterTrust).
.SAFE SafeIT encyrpted file/attachment. Original filename with extension has the SAFE extension appended to it once encryption is completed (SoftNet Security's SafeIT Encryption v6).
.SAM  Ami Pro document (Many word processor and Office applications).
.SAM  Headerless 16-bit monophonic audio sample file (Many audio applications).
.SAM  Session file (MAGIX Music Studio).
.SAMPLE Sample file = TXT file (Ares Galaxy and others).
.SAMPLE Sample file whose content usually is that of a file with a different extension (Many applications).
.SAP  Atari SAP audio file.
.SAS  SAS source code file.
.SAV  Backup files (Many applications).
.SAV  Game Save file (Activision Mech Warrior 2).
.SAV  Game Save or Auto-game-save file (Valve, Westwood, FreeCiv, and other games/developers).
.SAV  Project or application state Save files (Many applications).
.SAZ  Session Archive ZIP format (Fiddler web debugger).
.SBD  Storyboard file (MGI VideoWave, a few variants).
.SBE  SpyBot Excludes file = DOS text (Safer-Networking's Spybot Search & Destroy).
.SBI  SpyBot Search & Destroy's Includes file = spyware detection database (Safer-Networking's OpenSBI Editor and SpyBot Search & Destroy).
.SBL  StarBasic Language file (Sun's StarOffice 5.1).
.SBS  SpyBot Search & Destroy Supplemental spyware detection database file (Safer-Networking's SpyBot Search & Destroy).
.SC   SuperCollider file (James McCartney and others' SuperCollider).
.SC2  Schedule+ application file (Microsoft Office).
.SC9  Suitcase 9 font database file (Extensis Suitcase 9).
.SCA  Scenery Assembler source file for creating Microsoft Flight Simulator 5 map sceneries (Manfred Moldenhauer's SCASM/Scenery Assembler).
.SCALA Scala programming language source code file.
.SCAMFS Saved audio file search parameters = UTF8 text (ScanFS).
.SCANFS_CATALOG Audio file catalog (ScanFS).
.SCC  StarOffice storage document (StarOffice Writer 5.1).
.SCD  Animated Screen Data file (3D GIF Designer).
.SCD  Schedule+ application file (Microsoft Office).
.SCD  Scribus Document format same as SLA (Scribus).
.SCD  SuperCollider language file (James McCartney and others' SuperCollider).
.SCE  Scribus object file (Scribus).
.SCE  Secure/encrypted file (SoftNet Security's SafeIT Encryption).
.SCH  Schedule+ application file (Microsoft Office).
.SCH  Circuit Schematic file (Michael Margraf's QUCS/Quite Universal Circuit Simulator).
.SCHLP SuperCollider Help file (James McCartney and others' SuperCollider).
.SCI  SciFAX image file (Many graphics applications).
.SCM  Sound Scheme file (ICQ2000a).
.SCM  Scheme programming language source file.
.SCN  Auto-saved game (LinCity-NG) User saved games are same format without the extension.
.SCN  Caligari trueSpace Scene file (Caligari trueSpace and many applications and environments).
.SCN  LightWave Scene file (LightWave Studio).
.SCN  Scenario file (Microsoft's Age of Empires 2).
.SCN  VideoWave Scene file (MGI VideoWave 5).
.SCO  Score file (Many audio/music composing/creating applications).
.SCP  Script file (Many applications).
.SCPT AppleScript file (Applications supporting the AppleScript scripting language).
.SCR  Frame script file (OpenFX Animator).
.SCR  Monitor/Screen configuration file.
.SCR  Scratchpad file (CIX's Ameol2).
.SCR  Screen image file (ZX Spectrum computer).
.SCR  Screensavers (Microsoft Windows).
.SCR  Script file (Half-Life game engine).
.SCR  Word 5.x Screen Capture image file (Microsoft Word and image editors).
.SCRATCHP Archived Scratchpad file (CIX's Ameol2).
.SCSU Unicode compressed file (Andrew West's BabelPad).
.SCT  SciTex Continuous Tone image file (Many graphics applications).
.SCT  Screen Template file (Microsoft Visual FoxPro 6).
.SCT  Script file.
.SCX  Form file (Microsoft Visual FoxPro 6).
.SD   Script Definition file (Visicom Media's AceHTML Pro).
.SD   Sound Designer audio file (Sound Designer and other applications).
.SD2  Sound Designer 2 audio file (QuickTime 7.7.2).
.SD4  Smart Diary Suite version 4 diary database file (Programming Sunrise's Smart Diary Suite 4).
.SD4-JOURNAL Smart Diary Suite version 4 Journal file (Programming Sunrise's Smart Diary Suite 4).
.SD4LF  Smart Diary Suite version 4 Life Factors package file (Programming Sunrise's Smart Diary Suite 4).
.SD6  SafeIT address book file (SoftNet Security's SafeIT Encryption v6).
.SDA  Self-Dissolving Archive (Formats unique to each machine supporting such formats).
.SDA  StarDraw image file (StarOffice Draw 5.1).
.SDADDIN Sharp Develop AddIn installation package file (sharpdevelop.net's JSharp Develop 4).
.SDB  SafeIT address book Database file (SoftNet Security's SafeIT Encryption).
.SDC  StarCalc spreadsheet file (StarOffice Calc 5.1).
.SDD  StarImpress presentation Document file (StarImpress Writer 5.1).
.SDE  Equaliser settings file (Steven Mayall's MusicBee).
.SDF  SQL Server Database File (Many applications).
.SDF  System Data Format file = simiular to CSV and TSV, a file with fixed-length records delimited by a carriage return and line feed characters (Database applications).
.SDG  Clip art thumbnail Gallery resource (IBM Lotus Symphony).
.SDL  Service Description Language file (Microsoft VisualStudio).
.SDL  SmartDraw image/shape Library file (SmartDraw).
.SDM  StarMessage 5.0 e-mail file (Sun's StarOffice StarMessage e-mail client).
.SDP  Session Description Protocol (QuickTime 7.7.2).
.SDR  SmartDraw Drawing file (SmartDraw).
.SDS  SpyBot Search & Destroy Script file (Safer-Networking's SpyBot Script Editor 2).
.SDS  StarOffice binary Chart file (Older versions of Sun's StarOffice).
.SDSB SpyBot Search & Destroy Script Binary file = compiled script(Safer-Networking's SpyBot Script Editor 2).
.SDT  SmartDraw Template drawing file (SmartDraw).
.SDV  3GPP movie (QuickTime 7.7.2).
.SDV  SmartDraw Advisor image file (SmartDraw).
.SDW  StarWriter document file (StarOffice Writer 5.1).
.SEA  Macintosh OS Self-Extracting Archive file (SmithMicro Stuffit).
.SEC  Secure/encrypted file (SoftNet Security's SafeIT Encryption).
.SEL  EzyPage file (EzyWare's EzyPage).
.SES  Multi-track Session file (Syntrillium Cool Edit Pro).
.SESSION Saved Session file (Neil Hodgson's SciTE).
.SESX Multi-track Session file (Adobe Audition).
.SET  Character mapping base Set file (Word Perfect Office X6).
.SETTINGS Settings file (Cinta Software's CintaNotes).
.SF2  E-mu/Creative SoundFont 2 MIDI file (Many applications).
.SFARK SoundFont Archive file = compressed SoundFont file (Many audio/arrangement applications).
.SFARR SynthFont Arrangement file (Kenneth Rundt's SynthFont).
.SFD  Commodore SFD 1001 disk drive disk image file (Commodore computer emulators).
.SFD  Source File Data file = Font glyph data (FontForge).
.SFF  Elecbyte Sprite File (Jon Rafkind's Paintown).
.SFS  Orion Song Files (Sonic Syndicate Orion).
.SFS  StarFrame Frameset document file (StarOffice Frame 5.1).
.SFW  Sound Forge Workspace file (Sonic Foundry Sound Forge).
.SGF  Sonique player Skin file (Sonique Media Systems).
.SGI  SGI truecolor image file (Many image editors).
.SGL  StarWriter master/Global document file (StarOffice Writer 5.1).
.SGM  SGML template file / auto-file (Word Perfect Office X6).
.SGN  Sign document file (Sierra On-Line's Print Artist 3).
.SH   Command line Bash Shell script = batch of consecutively executed shell commands (Bash shell on Unix/Linux OSs).
.SH   Mindjongg saved game (Minder Mindjongg).
.SH3  Harvard Graphics format image.
.SH3D Sweet Home 3D project file = ZIP archive.
.SHADE RayShade file (Lintermann und Deussen's/Greenworks' XFrog 3 and other applications).
.SHADOW Shadow file (Neuber Font Twister).
.SHAPE Vector-based grayscale shape image (Dia).
.SHD  Bryce 2 materials file (MetaCreations Bryce 2).
.SHG  Segmented Hypergraph image file (Ulead Video Paint and other graphics applications).
.SHN  Shorten audio file = a popular compressed lossless audio format (Many audio editing/playing applications).
.SHP  ESRI Shape file (Autodesk 3DStudio, LibreCAD, CorelCAD, and many other drawing/modelling applications).
.SHP  Shalom Help Project file (Shalom Help Maker).
.SHW  Presentations file (Corel Presentations).
.SHX  Shape file.
.SID  MrSID image file (LizardTech MrSID).
.SID  SID chip music file (SIDPlayer and other 6581/SID chip emulating players).
.SIDX Stuffit Deluxe Extended format archive file (SmithMicro Stuffit Deluxe and Stuffit Expander).
.SIF  Setup Information File (driver installers - SiS, Cmedia, and others).
.SIFZ Synfig animation image file (Synfig Studio).
.SIG  Sign/poster project file (MindScape PrintMaster).
.SIMDT Software Ideas Modeller Documentation Template file (Dusan Rodina's Software Ideas Modeller).
.SIMP Software Ideas Modeller Project file (Dusan Rodina's Software Ideas Modeller).
.SIMSS Software Ideas Modeller StyleSets file (Dusan Rodina's Software Ideas Modeller).
.SIMT Software Ideas Modeller Template file (Dusan Rodina's Software Ideas Modeller).
.SIRENSKIN Siren Skin file (Sonic Foundry Siren/SirenXpress).
.SIT  Stuffit format archive file (Stuffit Deluxe, Stuffit Expander and other archiving applications).
.SITX Stuffit Extended format archive file (SmithMicro Stuffit Deluxe and Stuffit Expander).
.SKA  SSEYO Koan Album file (SSEYO Koan Album Player).
.SKB  SketchBoard sketch data file (Pojchara Jatupoj's SketchBoard).
.SKD  SSEYO Koan Design file (SSEYO Koan Album Player).
.SKF  SketchUp thumbnail image file (Autodesk SketchUp).
.SKL  System Library file (Windows).
.SKM  SSEYO Koan Mix file (SSEYO Koan Album Player).
.SKN  Skin file (Earjam Internet Music Player 1.0).
.SKP  SketchUp Component file (Autodesk SketchUp, Google Sketchup, and others).
.SKP  SSEYO Koan Play file (SSEYO Koan Album Player).
.SKT  SSEYO Koan Template file (SSEYO Koan Album Player).
.SL   SL file (Timothy M Shead's K-3D 0.8).
.SLA  Scribus Layout format document. UTF-8 encoded XML document native to the open source Scribus desktop publishing application. A few variants of the format, though all should handle them correctly.
.SLD  Slide file (Pierre-e Gougelet's XnView).
.SLD  Styled Layer Descriptor file (GeoServer 2).
.SLK  SYLK format spreadsheet or formulas file (Many Office applications).
.SLMETA SLMETA file (Timothy M Shead's K-3D 0.8).
.SLN  Solution file (Microsoft VisualStudio).
.SLN  Solutions file (sharpdevelop.net's JSharp Develop 4).
.SLP  SLP file (ArtDesk SLP Writer).
.SLP  SLP render file (Parametric Technologies' Pro/Engineer).
.SMD  StarMessage Document file (Sun's StarOffice StarMessage e-mail client).
.SMF  MIDI (QuickTime 7.7.2).
.SMF  Simple Model Format file (Leadwerks 3D World Studio).
.SMF  StarMath Mathematical Formula file (Sun's StarOffice StarMath).
.SMI  SmartIcons bar configuration file (Lotus Development's Lotus Organizer).
.SMI  SMIL (QuickTime 7.7.2).
.SMIL SMIL (QuickTime 7.7.2).
.SMIS Submitter Mission file (FirstPlace Software's WebPosition Gold).
.SMK  Smacker archive file.
.SML  Shape Markup Language image format. Vector based grayscale image (Kivio and other applications).
.SML  SMIL (QuickTime 7.7.2).
.SMP  NN19 Sampler device patch file (Propellerhead's Reason).
.SMP  Sound sample/audio file (SampleVision).
.SMTP SMTP mailserve locations file (DesertFish Roamer).
.SNAPSHOT Snapshot of storage usage in mixed file of ANSI and UTF8 (Saleen Software File Pro - A Spacemonger clone in Delphi).
.SND  AU audio (QuickTime 7.7.2).
.SNIPPET Code Snippet file (Microsoft VisualStudio).
.SNP  Snapshot file (Microsoft Snapshot Viewer).
.SO   Source or splash screen file (Cincom VisualWorks SmallTalk).
.SO   Subversion Object file (Tigris Subversion).
.SOB  Caligari Object file (Caligari for the Amiga OS).
.SOB  StarOffice BASIC application (Sun's StarOffice and OpenOffice suites).
.SOC  StarOffice Configuration file (Sun's StarOffice and OpenOffice suites).
.SOD  StarOffice Definition file (Sun's StarOffice and OpenOffice suites).
.SOE  StarOffice Extension file (Sun's StarOffice and OpenOffice suites).
.SOS  SingOutStrong playlist file (Jan Fabirkiewicz' SingOutStrong Karaoke Player).
.SOU  Source code file (Cincom VisualWorks SmallTalk).
.SP6  SafeIT Secure Profile file (SoftNet Security's SafeIT Encryption v6).
.SPA  Splash movie (Macromedia FutureSplash and Flash supporting applications).
.SPD  form-Z Susp render file (form-Z RadioZity).
.SPF  Crontab file (ActiveState's Komodo Edit).
.SPF  Shorthand glossary file (Bartels Media PhraseExpress).
.SPL  Splash file (Macromedia FutureSplash and some Flash supporting applications).
.SPOP Inter Trust file.
.SPP  Serif PhotoPlus animation file (Serif PhotoPlus).
.SPP  Serif PhotoPlus Picture file (Serif PhotoPlus).
.SPR  Screen Program file (Microsoft Visual FoxPro 6).
.SPX  Ogg Speex format audio file (Many audio applications).
.SQL  SQL database file (Many applications).
.SQL  Structured Query Language source code or procedure file (Many variants, operating systems, and applications).
.SQLITE SQLite database file (Many applications).
.SQT  Squirt save file (Squirt/ISQ).
.SR2  Sony RAW Format image file (Sony cameras, many image applications, many variants).
.SRB  Scrapbook file (Word Perfect Office X6).
.SRF  Sony RAW Format image file (Sony cameras, many image applications, many variants).
.SRI  Scrapbook Index file (Word Perfect Office X6).
.SRL  Secure Request Letter = plaintext e-mails/messages to recipients (SoftNet Security's SafeIT Encryption).
.SRP  Script files (various programs).
.SRT  SubRip format sub-titles file (Aegisub).
.SRT  SubRip format sub-titles file (Many media player applications).
.SS   Slide Show Project file (Anix Software's MySlideShow 2).
.SS   Scheme programming language source file.
.SS   Simple Sudoku format saved game file (SimpleSudoku, Bernhard Hobiger's HoDoKu and other Sudoku games).
.SSA  Advanced Substation Alpha format sub-titles file (Aegisub).
.SSD  SnagIt Studio project file (TechSmith SnagIt).
.SSF  Slideshow File (Bruno Cancelleri Pictoscope).
.SSG  Scrabble3D Saved Game file (Heiko Tietze's Scrabble3D).
.SSK  SmartSketch drawing format image file (Macromedia SmartSketch/Flash MX and other Flash applications).
.SSM  Standard Streaming Metafile (Real Networks' RealPlayer 7).
.SSP  Screen Saver Project file (MGShareware Screen Saver Builder).
.SSP  SSuite format Presentation file (SSuite Office Presentations).
.SSS  Soysal Setup batch command file (Soysal Setup Interpreter).
.SST  Microsoft Serialized certificate Store file.
.SSX  Slide Show Project file (Anix Software's MySlideShow 3).
.ST   SmallTalk file-outs file (Cincom VisualWorks SmallTalk).
.STAT Statistics file (Ari Pikivirta's Home FTP Server).
.STC  StarOffice Calc Template file = XML based file (Sun's StarOffice and other OpenOffice suites).
.STD  StarOffice Draw Template file = XML based file (Sun's StarOffice and other OpenOffice suites).
.STD  Sure Thing CD label, card, or jewel case Design file (Sure Thing CD Labeler).
.STDL-BACKUP Swift To Do List database auto-backup file (Dextronet Task List Guru).
.STDL Swift To Do List database file (Dextronet Task List Guru).
.STEP STEP geometry file.
.STH  SampleTank instrument Header file (VST sound module requires .STI and .STW).
.STI  SampleTank Instrument program file (VST sound module requires .STH and .STW).
.STI  StarOffice Impress Template file = XML based file (Sun's StarOffice and other OpenOffice suites).
.STI  Sticker project file (MindScape PrintMaster).
.STK  Stock file (DTLink Software's Personal Stock Monitor 5).
.STL  EBU Sub-Titling data exchange format file (Aegisub).
.STL  Stereo Lithography file (Many molding, modelling and prototyping applications and devices).
.STP  e-Store Project file (Trellian eCommPRO).
.STT  Say The Time reminders file (Impaque Technology's Say The Time).
.STT  Sure Thing CD template file (Sure Thing CD Labeler).
.STUFFITTASK Stuffit Task file (SmithMicro Stuffit Deluxe).
.STW  SampleTank instrument Waveform file (VST sound module requires .STH and .STI).
.STW  StarOffice Writer Template = XML based file (Sun's StarOffice and other OpenOffice suites).
.STY  Story file = text (Stepware's AceReader Pro).
.STY  Style file (Pixel Studio Pro).
.SUB  MicroDVD format sub-titles file (Many media player applications and sub-title editors).
.SUB  Sub channel data file for audio discs (Many disk image writer/creator applications).
.SUB  Subvein map file (Ben Johnson's Subvein).
.SUP  PGS/SUP subtitles file (Video audio applications).
.SVA  Sensiva plug-in Application file (Sensiva for Windows 2).
.SVE  Saved game file (Simutrans).
.SVG  Scalable Vector Graphics (Many).
.SVG  Scalable Vector Graphics 2D image format. An open standard that is well supported by many applications.
.SVGZ Compressed Scalable Vector Graphics 2D image format.
.SVI  Samsung format Video file (Samsung products and third party supporting applications).
.SVM  Sensiva Action file (Sensiva for Windows 2).
.SVM  StarView Metafile = SVG file (Sun's StarOffice 5.1).
.SVS  Sensiva Symbol file (Sensiva for Windows 2).
.SVT  Sensiva sound Theme file (Sensiva for Windows 2).
.SVX  Amiga 8SVX format IFF audio file (Audio editor/player applications).
.SWA  MPEG Layer-3 audio (QuickTime 7.7.2).
.SWF  Shockwave Flash movie file (Macromedia Flash and third party Shockwave/Flash supporting applications).
.SWP  Screen Writer Project file (Virtual Amnesia's Screen Writer Pro).
.SWP  Swap file (Dyvision Works' Advanced Landscape Editor).
.SWT  Template file (Macromedia Generator).
.SXC  StarOffice XML Calc file (Sun's StarOffice and other OpenOffice suites).
.SXD  OpenOffice Drawing vector based image format. Like ODG image files, these enjoy support in the open source Office suites, and third-party Office programs.
.SXG  StarOffice XML master document (Sun's StarOffice and OpenOffice suites).
.SXI  StarOffice XML Impress document (Sun's StarOffice and OpenOffice suites).
.SXM  StarOffice XML Math formula file (Sun's StarOffice and other OpenOffice suites).
.SXT  NNXT Sampler device patch file (Propellerhead's Reason).
.SXW  StarOffice XML Writer document (Sun's StarOffice and other OpenOffice suites).
.SY3  Harvard Graphics format image.
.SYLK Symbolic Link interchange format file (Many applications).
.SYN  Synthesizer instrument file (FruityLoops, SimSynth, and other samplers, mixers, and trackers).
.SYX  Raw SysEx file (MIDI, sequencer, sampler and other audio applications).
.T3D  UnrealEd brush format file.
.T64  Cassette Tape image file = WAV/Waveform audio content created by/for numerous Commodore computer emulators (Nicola Salmoria & MAME team's MAME and other emulators).
.T64  Commodore C2N tape drive emulator image used by Commodore computer emulators.
.TAB  Crontab file (ActiveState's Komodo Edit).
.TAG  TagInfo file identifying software and product/device it is intended for (driver installers - Intel, etc.).
.TAK  Tom's lossless Audio Kompressor (TAK library and many audio applications).
.TAR  TAR archive file = Tarball = a simple, uncompressed container file, often GZ-compressed "TAR.GZ" (Many applications).
.TASDB Archive System Database Template file (Sayyid Mohammad Saleh Samimi's Archive System 1.9).
.TASKS Task list file (Digia Qt Creator).
.TBR  Toolbar resource file (Joseph Hardy's PageCraft 2).
.TBR  TwistedBrush image file (Pixarra TwistedBrush Pro Studio).
.TBS  TeraByte Scripting language file = plain text (TeraByte BootIt Bare Metal and other TeraByte products).
.TBS  TuneUp Styler Boot Screen file (TuneUp Utilities).
.TBWML Text Block Writer Markup Language file = native document format (SoftwareByBrian's Text Block Writer).
.TCL  Tool command language/Tcl programming/scripting language source file (Tcl/Tk 8 toolkit and many text editors).
.TCL  Text Clip Library file (Text editors and Windows clipboard monitors).
.TDY  Tidy settings file (Raggett's HTML Tidy and other web page/site developer applications).
.TED  Terrain Editor file (D-Graphics' Terrain Editor/T.ED).
.TEG  Transition Effect or media clip file (Ulead Systems Media Studio 5 Video Editor).
.TEST Java Test file (Java applications).
.TEX  LaTeX file (Many applications/text processors).
.TEX  Texture file (Many graphics applications).
.TEX  Texture image file (Jasc Paint Shop Pro).
.TEXCACHE NetImmersive/Gamebryo model File (NifTools NifSkope).
.TEXTER Texter text snippets file (Bartels Media PhraseExpress).
.TEXTEXPANDER TextExpander text snippets file (Bartels Media PhraseExpress).
.TEXTURE Creative Assembly DXT1 texture file (Martin Wright's DXTBmp Editor).
.TGA  TGA format image file (Many applications, 2 format versions 1 and 2. Often called TARGA/Truvision image).
.TGD  Terragen 2 project/Document file (Planetside Terragen 2).
.TGF  Trivial Graph Format file (yWorks' yEd Graph Editor).
.TGO  Terragen Object file (Planetside Terragen 2).
.TGP  Terragen Plug-in file (Planetside Terragen 2).
.THD  Header index file (CIX's Ameol2).
.THE  The Hessling Editor file = text document (Mark Hessling's The Hessling Editor).
.THERC The Hessling Editor Resource file (Mark Hessling's The Hessling Editor).
.THL  Thumbnail images in bitmap format (Cyberlink PowerProducer).
.THM  Clip art Theme title and resources index file (IBM Lotus Symphony).
.THM  Skinning Theme files (DreamQuest Championship Euchre, Hearts, & Spades).
.THM  Theme file (Many).
.THM  Thumbnail image file, often sharing the same file name of a resource file whose content it illustrates (Varying types, usually JPEG, TIFF, PNG, or some form of bitmap, many applications).
.THT  Table Hockey Tournament file (Lasse Rautiainen's Table Hockey Tournament Scheduler).
.TIF  Tag Image File format (Many graphics applications).
.TIF  Tag Image File Format bitmapped image (Aldus Corporation - Numerous variants and programs).
.TIFF Tag Image File Format (Aldus Corporation - Many graphics applications).
.TIFF Tag Image File Format bitmapped image (Aldus Corporation - Numerous variants and programs) A preferred format in commercial printing for it's lossless images with good compression, PostScript, CYMK, and ICC profile support.
.TIMELINE Timeline project file (Insane Tools' 3D Flash Animator 3).
.TIP  Application usage Tips file (ACD Systems' ACDSee v3.1).
.TIP  TuneUp Icon Package file (TuneUp Utilities).
.TIXATICONFIG Tixati Configuration file (Tixati torrent client).
.TLS  TuneUp Logon Screen file (TuneUp Utilities).
.TLX  User dictionary files (e-Press EasyOffice).
.TLZMA LZMA-compressed Tarball file (SmithMicro's Stuffit Deluxe 2010).
.TMB  Thumbnail image file = bitmap image (MediaChance Real-DRAW).
.TMD  TextMaker Document file (SoftMaker Office TextMaker).
.TML  TimeLine project file (SoftLab's DDClip Pro).
.TMPL eMule Template (eMule P2P clients and mods).
.TMV  TextMaker Template file (SoftMaker Office TextMaker).
.TNF  Thumbnail File (Bruno Cancelleri's Pictoscope).
.TNFO Internal Information file (SpyBot Seek & Destroy).
.TOC  Table Of Contents file.
.TOM  Task-O-Matic task list file (Pollen's Task-O-Matic).
.TORRENT Torrent file (BitTorrent's µTorrent and other torrent/file-sharing applications).
.TPL  Template file (KetilO's FbEdit FreeBASIC Editor, Fookes Holdings' NoteTab and other text editors).
.TPL  Template file (Many formats and applications).
.TPL  Template file (Twelve Tone's Cakewalk).
.TPL  Web project Template file (ixla Web Easy).
.TPS  Paper Space Template file (Upperspace's DesignCAD 3D MAX).
.TRAY Corel Connect 3 Tray file (Corel's CorelDRAW X6).
.TRAY~ Temporary Corel Connect 3 Tray file (Corel's CorelDRAW X6).
.TRC  Traces animation file (Berkeley Systems After Dark Deluxe 4).
.TRI  Triangle binary file = geometry data in triangular format (Alias Research's Power Animator/Studio and other applications).
.TRK  Track summary file (CFB Software's LP Ripper).
.TRS  Transcriber annotation file = XML markup (Media transcription applications and supporting players).
.TS   Message catalog file.
.TS   MPEG video file (Many applications).
.TSB  TriSpectives WorkBook file (3D/EYE's TriSpectives).
.TSC  TriSpectives Catalog file (3D/EYE's TriSpectives).
.TSH  T-Shirt project file (MindScape PrintMaster).
.TSK  Task parameters (SomeWare d'peg! Cicada).
.TSP  StylePix image project file (Hornil StylePix).
.TST  Test file with answers marked = text (Stepware's AceReader Pro).
.TSTREAM TStream file (Tribler).
.TSV  Tab-delimited Log file (Microsoft Windows Performance Monitor).
.TSV  Tab Separated Values file = Data values delimited by a single tab character.
.TT   Text Template file (Microsoft Visual Studio 9).
.TTA  TrueAudio audio file (Many audio applications).
.TTC  True Type Font file.
.TTF  True Type Font file (Many applications).
.TTXT MPEG4 Timed Text format sub-title file (Media player applications and hardware).
.TUB  Tube file (Jasc Paint Shop Pro).
.TUN  Microtuning file = permits adjustments of VSTi instrument effects tonal qualities (LinPlug Virtual Instruments' Albino2FX).
.TVS  TuneUp Visual Styler visual style format (TuneUp Utilities).
.TWS  TextPad Workspace file (Helios Software TextPad).
.TX   ADTdirect dummy loader file (CorelCAD).
.TX   Text file.
.TXR  Multi-language Text Resource file (Difitec WavePurity).
.TXT  Text file (Most applications and operating systems).
.TXT+ Encoded text file - similar to ROT13 (Fortel's VisualRoute 5).
.U    Unreal Tournament game file (Digital Extremes & Epic Games Unreal Tournament/UT).
.U32  User Code for 32-bit Windows Authorware applications (Macromedia Authorware 6).
.UAE  Amiga Emulator configuration file (WinUAE).
.UBX  RP file (Axure RP Pro).
.UCD  User Code for 16-bit Windows Authorware applications (Macromedia Authorware 6).
.UCG  Ulead CG Infinity project file (Ulead CG Infinity).
.UDF  Universal Disc Format CD ISO image file (CD burner applications).
.UENC UltraEdit Encrypted file (IDM Computer Solutions' UltraEdit).
.UEZ  ULEAD Exported presets from previous versions (ULEAD Cool 3D 3.5).
.UFO  Ulead File for Objects file (Ulead PhotoImpact).
.UFRaw ID files (UFRaw).
.UI   Qt Designer file (Digia Qt Creator).
.UI   UltraISO image file (EZB Systems UltraISO).
.UID  User Identity file (ICQ2000a).
.UIF  UIF image file (Power Software's Free Any Burn).
.UIS  Ulead Image Sequence file with RIFF header (Ulead's VisualStudio 6, Ulead Video Paint and other Ulead products).
.UIS  User Interface Style file = proprietary-stored-in-plaintext "WindowBlinds Advanced Visual Style format" (Stardock's WindowBlinds, ObjectDock and other Stardock products).
.ULW  AU audio (QuickTime 7.7.2).
.UML  Unified Modelling Language diagram file (Diagramming/modelling software).
.UMX  Unreal Music Package file (Ian Luck's XMPlay module/mod player).
.UOL  Ulead Object Library (Ulead PhotoImpact 7).
.UP2  Ulead Plug-in list file (Ulead Cool 3D, Ulead Web Razor).
.UPD  UPD file = URL of currently playing audio track (Steven Mayall's MusicBee).
.UPD  Ulead Board Plug-in file (Ulead Cool 3D, Ulead Web Razor).
.UPF  UGH Burner Project File (A.L.U.Tech's UGH Burner).
.UPI  Ulead PhotoImpact Image file (Ulead PhotoImpact and other Ulead applications).
.UPP  Ulead Program file (Ulead Systems' MediaStudio 5).
.URA  URL Address Book file (GBCS' URL Address Book).
.USF  USF subtitles file (Video audio applications).
.USK  UltraSkins file (UltraCo UltraPlayer).
.USR  Custom User database file (Corel PerfectExpert Assistant).
.UTF8 UTF8 text file (Many applications).
.UTX  Unreal Tournament 2003 Texture file (Digital Extremes & Epic Games Unreal2003).
.UU   UUencoded file (Archivers, Usenet newsreaders, browsers, and other applications).
.UUE  UUencoded file (Archivers, Usenet newsreaders, browsers, and other applications).
.UV   UVIEW file (Cinegraphics' UVIEW and other applications).
.UVP  Ulead Video Paint project file (Ulead Video Paint).
.UVS  UltraVisualization file (UltraCo UltraPlayer).
.V    Verilog sources file (Michael Margraf QUCS/Quite Universal Circuit Simulator).
.V    Vi text file (Unix/Linux and other variants of the Vi text editor).
.VA   Verilog-A sources file (Michael Margraf's QUCS/Quite Universal Circuit Simulator).
.VALIDBAK backup file (Saleen Software Task Manager).
.VB   VB.NET file (sharpdevelop.net's JSharp Develop 4).
.VB   VisualBasic source code file (Microsoft VisualBASIC).
.VBA  VisualBasic for Applications code (Many applications).
.VBF  ViPlay Bookmark File (UruSoft ViPlay).
.VBPROJ VB.NET Projects file (sharpdevelop.net's JSharp Develop 4).
.VBPROJ VisualBASIC Project file (Microsoft VisualStudio/VisualBASIC).
.VBSL VisualBasic Scripting Language script file (Microsoft VisualBasic).
.VCD  Virtual drive image file (Power Software's Free Any Burn).
.VCF  vCard File (SoftMaker Office eM Client, Microsoft Outlook and many other applications).
.VCL  VideoClick Link file (VSoft's VideoClick Personal).
.VCO  VideoClick Object file (VSoft VideoClick Personal).
.VCP  Axogon Composer Project file (Axogon Composer).
.VCPROJ VisualC++ Project or VisualStudio Project (Microsoft VisualStudio).
.VCS  vCalendar events/tasks file (StarOffice 5.1 and many other applications).
.VCX  Visual Class Library file (Microsoft Visual FoxPro 6).
.VDA  TGA format image file = TGA file.
.VDG  ViPlay DVD Graph file (UruSoft's ViPlay).
.VDI  VirtualBox Virtual Disk Image file (Power Software's Free Any Burn).
.VDR  Video Driver file (Macromedia Authorware 6).
.VDU  Detailer VDU version 2 file (Fractal Designs Detailer).
.VDX  Visio Document XML format.
.VEC  Video Editor media library Contents file (Online Media Technologies' AVS Video Editor).
.VEM  Video Edit Master project file (Hazem Osman's Video Edit Master 2).
.VEP  Video Editor Project file (Online Media Technologies' AVS Video Editor).
.VERT Vertex file.
.VET  Video Editor Title file (Online Media Technologies' AVS Video Editor).
.VEX  VGAPaint Extension file (Avery Lee's VGAPaint which is a DeluxePaint clone).
.VFJ  Verify Job file (Personal Backup).
.VFT  Video Filter plug-in file (Ulead Systems' MediaStudio 5, Ulead Web Razor).
.VFW  Microsoft movie (QuickTime 7.7.2).
.VFX  Video Effects plug-in file (Ulead Systems' MediaStudio 5, Ulead Web Razor).
.VFX  Visualization Effects file (Earjam Internet Music Player 1.0).
.VGA  Game file (Accolade's Elvira II - The Jaws of Cerberus).
.VGL  VoiceGuide call Log file (Katalina Technologies Voice Guide).
.VGP  VoiceGuide Protected telephony script file (Katalina Technologies' Voice Guide).
.VGS  VoiceGuide telephony Script file (Katalina Technologies' Voice Guide).
.VHD  VHDL sources file (Michael Margraf's QUCS/Quite Universal Circuit Simulator).
.VHD  Virtual PC Virtual Hard Disk image file (Power Software's Free Any Burn).
.VHDL VHDL sources file (Michael Margraf's QUCS/Quite Universal Circuit Simulator).
.VIF  ViPlay Initialization File (Urusoft ViPlay).
.VIP  Virtual Project file (MAGIX Music Studio 6).
.VIP  Virtual Project/arrangement file (MAGIX Music Maker/Studio).
.VIS-DLL Visualizations plug-in file (GreenForce-Player).
.VIS  StudioPro file (Strata's StudioPro and other applications).
.VIV  Vivo movie file (VivoActive Movie Player).
.VIVO Vivo movie file (VivoActive Movie Player).
.VJSPROJ Visual J# Project file (Microsoft VisualJ# "JSharp").
.VLOG VideoClick application/debug Log file (VSoft VideoClick Personal).
.VLP  Valadeo LiveSite Project or template file (Valadeo LiveSite Creator).
.VLT-JOURNAL Font service Vault Journal file (High-Logic Main Type).
.VLT  Font data Vault file (High-Logic Main Type).
.VMDK VMWare virtual Disk image file (Power Software's Free Any Burn).
.VMG  ViPlay Media Graph file (Urusoft's ViPlay).
.VOB  MPEG video with NAV packets (DVDAuthor GUI).
.VOC  Creative Voice audio file (Creative Soundblaster and other products).
.VOC  SoundBlaster VOC format audio file.
.VOR  StarOffice template file (Sun's StarOffice 5.1).
.VOX  Voxware encoded ADPCM format audio (Dialogic VOX, VCT Encoder, and other audio applications).
.VP   Presets file (Axogon Composer).
.VPD  PhotoDVD Project file (VSO Software's PhotoDVD 4).
.VPL  ViPlay Playlist file (Urusoft ViPlay).
.VR0  xReminder event/appointment file (Duality xReminder Pro).
.VRH  xReminder holidays data file (Duality xReminder Pro and Calendarscope).
.VRML Virtual Reality Markup Language world description file (Many 3D editors and environments).
.VSA  VideoScape format 3D object (VideoScape and other 3D editors).
.VSCONTENT Visual Studio community Content installer file (Microsoft Visual Studio 9).
.VSD  Microsoft Visio Document (Visio).
.VSDIR Visual Studio new project shortcut file (Microsoft Office XP).
.VSF  ViPlay Subtitles File (UruSoft's ViPlay).
.VSI  Visual Studio community Content installer file (Microsoft Visual Studio 9).
.VSP  VisiPics Project file (VisiPics).
.VSP  VisualStudio Project file (Ulead's VisualStudio 6).
.VST  TGA format image file = TGA file.
.VST  Virtual Studio Technology/VST instrument/sound module file (Cubase, Logic Audio, many other audio sequencing/composing/tracking applications).
.VST  Visio file (Microsoft Visio).
.VST3 VST instrument plug-in file (Adobe Systems' Audition).
.VSTEMPLATE VisualStudio project/item Template file (Microsoft VisualStudio).
.VSZ  ViPlay Skin ZIP archive file (Urusoft's ViPlay).
.VTF  Valve Texture Format file (Valve games).
.VTM  Virtual Tools Markup Language file (Allaire HomeSite).
.VTN  vTuner Station presets file (Nothing Else Matters' vTuner).
.VTS  Accel format spreadsheet/worksheet (Many spreadsheet/Office applications).
.VUE  Vue file (C Jain's Mountain 3D landscape generator).
.VUE  Vue file (Microsoft Visual FoxPro 6).
.VVD  Vivid element files (Minolta Vivid 3D scanner).
.VW   VolksWriter document (VolksWriter and other text editors).
.VWH  Valadeo Web Hosting provider file (Valadeo LiveSite Creator).
.VWL  VideoWave Libary file (MGI VideoWave 3 and 4).
.VWP  Voxware encoder Plug-in file (Macromedia Authorware 6).
.VWT  VideoWave library Thumbnail file (MGI VideoWave 1.5).
.WAB  Windows Address Book file (All Microsoft Windows versions).
.WAB~ Windows Address Book backup file (Microsoft Windows).
.WAD  WAD format container file (Many variations. Used primarily by game developers as a single resource file into which any content can be stowed and referenced. Numerous editors can be found to examine/extract a WAD's content).
.WAR  Java Web Application file (Many Java applications).
.WAR  Westwood Archive file (Westwood Studios games).
.WAV  MP3 encoded WAV audio file. These non-standard audio files occur in Windows Theme packages.
.WAV  Uncompressed waveform/PCM audio (Many audio applications).
.WAX  Windows audio playlist (Windows MediaPlayer).
.WAX  Windows media audio shortcut file (QuickTime 7.7.2).
.WB1  Quattro Pro spreadsheet file.
.WB2  Quattro Pro 6 spreadsheet file.
.WB3  Quattro Pro v7 & v8 spreadsheet file.
.WBK  Word Backup file (Microsoft Word).
.WBMP Wireless Bitmap image file (CoffeeCup Wireless Image Maker).
.WCD  Works Catalog Database file (Microsoft Works).
.WCL  Windows Configurator Language file (Leszek Skorcsynski's Windows Configurator).
.WCM  Word Perfect PerfectScript macro file(Corel Word Perfect Office X6).
.WDC  Wondershare DemoCreator project file (Wondershare DemoCreator).
.WEB  Web page project file (MindScape PrintMaster).
.WEB  Web project file (ixla Web Easy).
.WEBFERRETSEARCH Web Ferret Search initiate file = launches a webFerret search using preconfigured search terms (FerretSoft's Web Ferret 3).
.WEBSPLIT Websplit file (Websplit).
.WEBTEST Visual Studio Web Test file (Microsoft VisualStudio).
.WFS  Wondershare Fantashow project file (Wondershare Fantashow).
.WGP  WinGuage saved guages properties/configuration file (Helix Software Nuts & Bolts).
.WI   Wavelet compressed Image file (Many applications).
.WIM  Windows Image file (Windows System Image Manager).
.WIN  Truevision image file (Brian Shepherd's Image Ax).
.WIN  Truevision image file (Many applications).
.WINGS Wings 3D project file (Björn Gustavsson's Wings 3D).
.WINMERGE WinMerge project file. UTF-8 encoded XML document defines project resources.
.WIT  Windows Insight Trace file = Active Directory event log entries (Microsoft Active Directory/AD Insight).
.WIXPROJ WIX Project file (sharpdevelop.net's JSharp Develop 4).
.WIZ  Scene creation Wizard file (MetaCreations Ray Dream Studio).
.WIZ  Wizard file (Microsoft Word).
.WIZHTML HTML template file (Microsoft Access 2002).
.WJF  WinZip Job File (WinZip).
.WK1  Lotus 1-2-3 v2.xx worksheet/spreadsheet (Lotus 1-2-3 v2.xx and many other spreadsheet applications).
.WK3  Lotus 1-2-3 v3.0 worksheet/spreadsheet (Lotus 1-2-3 v3.0 and many other spreadsheet applications).
.WK4  Lotus 1-2-3 v4/5 worksheet/spreadsheet (Lotus 1-2-3 v4/5 and many other spreadsheet applications).
.WKE  Lotus 1-2-3 Educational worksheet/speadsheet (Lotus 1-2-3 Educational edition/version and many other spreadsheet applications though far fewer supported the educational version).
.WKS  Lotus 1-2-3 v1/1-A worksheet/spreadsheet (Lotus 1-2-3 v1 and many other spreadsheet applications).
.WM   Windows Media audio/video file (QuickTime 7.7.2).
.WMA  Windows Media Audio file (Windows Media Player).
.WMDB Windows MediaPlayer Database file (Windows MediaPlayer).
.WMF  Windows Metafile. A vector based image format.
.WMI  Watermark Image configuration file (TSR Soft Watermark Image).
.WMI  Watermark Image file (TSR Watermark Image).
.WMP  Map file (3D Game Studio, Leadwerks 3D World Studio and other applications).
.WMX  Windows Media audio/video playlist (QuickTime 7.7.2).
.WND  Window file (Westwood Studio's NOX).
.WNV  Winnov WNV1 video file = video stream requiring the Winnov WNV1 codec.
.WP   WordPerfect Document (Many WordPerfect variants).
.WP~  WordPerfect document backup file (Many word processors).
.WP4  WordPerfect version 4 document (WordPerfect 4.x).
.WP5  WordPerfect version 5 document (WordPerfect 5.x).
.WP6  WordPerfect version 6 document (WordPerfect 6.x).
.WP7  WordPerfect version 7 document (WordPerfect 7.x).
.WPD  WordPerfect Document (WordPerfect, many versions and operating systems).
.WPD  WordPerfect Screen Driver file.
.WPE  Word Perfect Encrypted document (Word Perfect Office X6).
.WPG  Word Perfect Graphic format image file (Corel Word Perfect, Presentations, and other Office/graphics applications, including Word Perfect).
.WPL  Windows Media playlist (QuickTime 7.7.2).
.WPM  Word Perfect Macro file (602Software 602Text).
.WPS  Word Perfect Signed document (Corel Word Perfect Office X6).
.WPS  Writer document file (Kingsoft Office Writer).
.WPT  Word Perfect Template file (Corel Word Perfect Office X6).
.WPT  WordGraph document Template file (SSuite Office WordGraph).
.WPT  Writer document Template file (Kingsoft Office Writer).
.WPU  WavePurity PCM/ADPCM/compressed audio file (Difitec WavePurity).
.WQ1  Spreadsheet file (Quattro Pro).
.WQ2  Spreadsheet file (Quattro Pro 5).
.WQC  Wondershare QuizCreator quiz project (Wondershare QuizCreator).
.WR1  Symphony 1.1 and 1.2 spreadsheet file (Symphony).
.WRK  Symphony 1.0x spreadsheet file (Symphony).
.WRK  Workspace file (Twelve Tone's Cakewalk).
.WRK  Workspace file = application file page/cache file (MindScape PrintMaster Publishing Suite).
.WRL  World file = VRML model markup (3D editors and environments, many variations).
.WRP  Warp gallery texture file (Micrografx Picture Publisher).
.WRZ  World file Zip archived (3D editors and environments).
.WS   Workspace file (Cincom VisualWorks SmallTalk).
.WSA  Westwood Studios Archive file (Westwood Studio games).
.WSA  Workspace file for Animation Shop (Jasc Animation Shop).
.WSCX Wondershare SurveyCreator survey project (Wondershare SurveyCreator).
.WSD  WordStar format Document file (WordStar and many word processor and Office applications).
.WSDL Web Service Description Language file (Microsoft VisualStudio).
.WSO  Windows Security Officer user data file (Eugene Mihailov's Windows Security Officer).
.WSU  Westwood Studios Uninstaller configuration file (Westwood Studios games).
.WSZ  WinAmp Skin ZIP archive file (WinAmp 2.x).
.WTBD Whyteboard image file (Steven Sproat's Whyteboard).
.WTV  Windows Media Center TV file.
.WV   WavPack format audio file.
.WVL  Wave audio album (SSuite Office Wave Player).
.WVX  Windows Media audio/video playlist (QuickTime 7.7.2).
.WW1 .WW3 Window Washer custom clean items (Webroot Window Washer 4).
.WX   wxBASIC source code or program file (David Cuny's wxBASIC).
.WZCONFIG WinZip Configuration File.
.WZJ  WinZip Job file (WinZip International's WinZip 16).
.WZL  Warzone 2100 Legacy file (Warzone 2100 Legacy).
.WZMUL WinZip Multi-User License registration file (WinZip International's WinZip 16).
.WZP  Winyl Zipped Skin Pack file (VinylSoft's Winyl).
.WZTHEME WinZip Theme installer file (WinZip).
.X    DirectX 3D object file.
.X    DirectX model file.
.X    X3D2 mesh map (UNGSoft's Visual Terrain Maker).
.X16  Xtras for 16-bit Windows Macromedia/Authorware applications (Macromedia Authorware 6).
.X2I  Settings file (XPS2Images Converter).
.X32  Xtras for 32-bit Windows Macromedia/Authorware applications (Macromedia Authorware 6, Macromedia Freehand, etcetera).
.X3D  Xara3D file (Xara3D).
.X64  VICE variation of the Commodore 1541/D64 disk drive format image file (VICE).
.XAML XAML markup file (Corel Word Perfect Office X6, Windows .NET Framework applications).
.XAUTOPF XML Auto Playlist File (Steven Mayall's MusicBee).
.XBA  StarOffice Basic language program (Sun's StarOffice and OpenOffice supporting Office suites).
.XBAP XAML Browser Application file (Corel Word Perfect Office X6).
.XBM  X BitMap format image (Many graphics applications).
.XCF  Native image file format of GIMP (GNU Image Manipulation Tool and other image applications).
.XDR  XML Data Reduced schema file (Microsoft VisualStudio).
.XEN  Xenu Link Sleuth file (Tilman Hausherr's Xenu Link Sleuth 1.x).
.XFDF Forms Document File (Adobe Acrobat and compatible applications).
.XFM  Transforms files (Syntrillium Cool Edit Pro).
.XFR  XFrog 3D file (Lintermann und Deussen's/Greenworks' XFrog 3).
.XFX  OpenFX file (OpenFX Animator).
.XGML XML Graph Markup Language file (yWorks' yEd Graph Editor).
.XI   Extended Instrument file = Fastracker 2 format (FruityLoops, Orangator, and other audio/sampler/tracker applications).
.XIF  Tag Image File Format file = TIFF file (Many graphics applications).
.XKEY Product registration Key file (Analinx Duplicatch).
.XLA  Microsoft Excel Add-in file (Microsoft Excel).
.XLB  Microsoft Excel Toolbar configuration file (Microsoft Excel).
.XLC  Microsoft Excel Chart file (Microsoft Excel).
.XLK  Microsoft Excel Backup file (Microsoft Excel).
.XLL  Microsoft Excel XLL Add-in file = an Excel library file (Microsoft Excel).
.XLM  Microsoft Excel Macros file (Microsoft Excel).
.XLP  Xleaner Plug-in file (More Than A Cleaner's Xleaner).
.XLS  Microsoft Excel format spreadsheet/worksheet file (Most Office application suites).
.XLSHTML  Microsoft Excel HTML Document file (Microsoft Excel).
.XLT  Microsoft Excel spreadsheet Template file (Microsoft Excel and many other Office application suites).
.XLW  Microsoft Excel Worskspace file (Microsoft Excel).
.XM   FastTracker II Module audio file (Many tracker/audio applications).
.XML  Extensible Markup Language file (Many applications).
.XML~ Temporary XML file (Corel's CorelDRAW X6).
.XMO  Movie driver file (Macromedia Authorware 6).
.XMP  XML Presets file (PhotoMatrixPro).
.XMR  XMedia Recode settings file (XMedia Recode 3).
.XMT  XML-based Template file (QuarkXPress Passport).
.XNEWSRC Usenet newsgroups and header indices (Xnews Usenet newsreader).
.XNK  Exchange shortcut Link file (Microsoft Outlook/Outlook Express).
.XNT  QuarkXPress Extension file (QuarkXPress Passport, Quark CopyDesk and other Quark products).
.XPI  Plug-in extension file = ZIP archive (Mozilla Firefox).
.XPL  XingMP3 Playlist file (Xing Technology's Xing MP3 Player).
.XPM  Bitmap image format from X-Window systems supporting up to 256 colors.
.XPM  Unix icon file (Hagen Wieshofer's Icon Edit Pro).
.XPM  X PixMap format image (Many graphics applications).
.XSL  Extensible Stylesheet Language file = an XML-based variant of a cascading style sheet/CSS file (Many applications).
.XSLT Extensible Stylesheet Language Transformation file (Microsoft VisualStudio and other applications).
.XSPF XML Shareable Playlist Format file (VLCTeam's VideoLAN client, Steven Mayall's MusicBee and many other media applications).
.XTC  XTrackCAD Tracks file (Timothy M Shead's K-3D 0.8).
.XTG  QuarkXPress Tags file (QuarkXPress, Quark CopyDesk and other Quark products).
.XTODVD ConvertXtoDVD project file (VSO-Software's ConvertXtoDVD).
.XTS  QuarkXPress XTension Set file (QuarkXPress Passport).
.XWV  Maelstrom synthesizer device patch file (Propellerhead's Reason).
.XXT  QuarkXPress XTension file (QuarkXPress Passport).
.XY   XyWrite format document (XYWrite III Plus and other word processors).
.Y    Bison file (GNU Bison).
.Y    Yet Another Compiler Compiler/YACC file.
.Y    Yellow CYMK color separation channel.
.Y    yEnc-encoded file (Archivers, Usenet newsreaders, browsers, and other applications).
.Y2K  Y2K issues file = documentation/text.
.YAL  Clipart file (Arts & Letters).
.YAZ  ZIP archive file.
.YBK  Yearbook file (Encarta).
.YCF  Yankee Clipper clipboard files (Yankee Clipper).
.YENC yEnc encoded file (Many applications, especially e-mail and Usenet news/mail.).
.YGF  yWorks binary Graph Format file (yWorks' yEd Graph Editor).
.YGP  yoshinoGRAPH project file (Harukazu Yoshino's yoshinoGRAPH).
.YGZ  Compressed yoshinoGRAPH project file (Harukazu Yoshino's yoshinoGRAPH).
.YMG  Yahoo Messenger Group file (Yahoo Messenger).
.YNC  yENC encoded file (Many applications, especially e-mail and Usenet news/mail file attachments).
.YR   Yellow Reader configuration file (Yellow Reader).
.YW5  yWriter 5 project file (Spacejock's yWriter).
.YWC5 yWriter 5 file (Spacejock's yWriter).
.YY   Bison file (GNU Bison).
.YY   Yet Another Compiler Compiler/YACC file.
.YYY  Desktop wallpaper file (SpotInc's ScanOffix Pro).
.Z    Z format compressed archive file (Many applications and OSs).
.Z01 .Z99 Split, non-standard ZIP archive file(WinZIP only).
.ZA$  Application menu Backup file (ZedTech's ZTreeWin).
.ZAA .ZAZ Part files (Split).
.ZAM  Application Menu file (ZedTech's ZTreeWin).
.ZAP  Zap Pack (CNET Zapper).
.ZCP  ZCAD Project file (Andrey M. Zubarev's ZCAD).
.ZGR  Groove file (BeatCreator, FruityLoops and other audio/sampler applications).
.ZHT  form-Z Heights file (form-Z RadioZity).
.ZIP  ZIP format archive file (Many applications, OSs, etc).
.ZLB  form-Z Library file (form-Z RadioZity).
.ZLOG Volume log file (ZedTech's ZTreeWin).
.ZMT  form-Z Material file (form-Z RadioZity).
.ZNC  Zinc data file (Ontrack Fix-It Utilities 3).
.ZOO  ZOO archive file (Many applications and OSs).
.ZPAQ ZPAQ archive file (PeaZip).
.ZPF  form-Z Preferences file (form-Z RadioZity).
.ZS4  Zwei Stein 4 audio/video project file (T@B's Zwei Stein 4).
.ZSF  ZipSafe 2.0 format vault file (Navaho ZipSafe).
.ZSG  Saved Game file (Studio-Blum Cult2).
.ZYP  Subtractor synthesizer device patch file (Propellerhead's Reason).