.??_  Files ending in "_" are often compressed install files of the same
          name (e.g., .EX_ expands to .EXE, .DL_ expands to .DLL, etc.)
  .A    UNIX Library  [UNIX]
        ADA Program
  .A01  ARJ Multi-volume Compressed Archive (can be 01 to 99) (also see .000)
  .A01 - .A10  OzWin CompuServe E-mail/Forum Access SYSOP File
  .A06  Lotto Pro 2002 Smart Number Ticket
  .A11  AIIM Graphic
  .A31  Authorware 3.x Library
  .A3D  Amapi 3D Modeling
  .A3K  Yamaha A3000 Sampler File
  .A3L  Authorware 3.x Library
  .A3M  Unpackaged Authorware MacIntosh File
  .A3W  Unpackaged Authorware Windows File
  .A41  Authorware 4.x Library
  .A4L  Authorware 4.x Library
  .A4M  Unpackaged Authorware MacIntosh File
  .A4P  Authorware File Without Runtime
  .A4W  Unpackaged Authorware Windows File
  .A51  Authorware 5.x Library
  .A5L  Authorware 5.x Library
  .A5W  Unpackaged Authorware Windows File
  .A64  Artist 64  [XnView]
  .A8   Cubicomp PictureMaker 24bit 3D Animation (DOS-based animation program; graphics cards external to computer; Cubicomp closed 1990)
  .A86  A86 Assembler Program File
  .AA   Audio Book File
        PROGNOSIS Automated Analyst Document File
  .AAB  Macromedia Authorware Binary
  .AAC  Advanced Audio Coding File
  .AAM  Authorware Shocked File
  .AAO  America's Army Map
  .AAS  Authorware Shocked Packet
  .AAT  Arcinfo Line Data Attribute Data (GIS-related file)
  .AB   Applix Builder File
  .AB2  Parson's Address Book
  .AB3  PhotoImpact Album File
  .AB6  AB Stat Data
  .AB8  AB Stat Data
  .AB$  AutoCAD Spooled Plot File
  .ABA  Palm Address Book File
  .ABC  Flowchart
        Musical Notation Language File (folk melodies originally)
  .ABD  AmBiz Bonus Calculator Data File
        Adventure Builder Database
  .ABF  Adobe Binary Screen Font
  .ABK  Corel Draw AutoBackup
        Any Automatic Backup
  .ABL  Maxagrid Avails Data File (text format)
  .ABM  HitPlayer Audio Album File
        Photo Impressions 2000 Album
        Album File (various)
  .ABO  Applix Builder Turbo File
  .ABR  Photoshop Brush
  .ABS  Abstracts
        MPEG Audio Sound File  [MPEG]
        PC GNU Compiler Output
        Abscissa Data File
        Optocat  [XnView]
  .ABT  The Arbiter Sports Official Schedule [Viewer]
  .ABW  AbiWord Document File
  .ABX  WordPerfect Address Book File
  .ABZ  AbszOrb (textured spinning orb creator)
  .AC   CaseWare Working Papers Client File
  .AC_  CaseWare Working Papers Compressed Client File
  .AC$  AutoCAD Undo Info
  .AC3  AC3 Audio File Format [DVD Maestro, DVD Conductor]
  .ACA  MS Agent Character File
        Project Manager Workbench File
  .ACB  ACBM Graphic Image
        AOL Cab Launcher (archived data file)
  .ACC  DR-DOS Viewmax File
  .ACD  Chromeleon Channel Raw Data
        Sonic Foundry Acid Music File
        allCLEAR Flowcharting File
        MS Agent Character Definiton File
  .ACE  The Ace Archiver Compressed File
        Aces200  [XnView]
  .ACF  MS Agent Character File
        Photoshop Custom Filter
  .ACG  MS Agent Preview File
  .ACH  Rockwell Software Logix 5 File
        Speccy Snapshot
  .ACI  ACI Development Appraisal
  .ACL  Corel Draw 6 Keyboard Accelerator
        MS Office AutoCorrect List
        ACL For Windows (data mining software)
        Access Control List
  .ACM  Audio Compression Manager Driver (Windows)
        Photoshop Command Button
        Windows System File
        ACBM Image File
        Interplay Compressed Sound File
  .ACO  Photoshop Color Swatch File
  .ACP  MS Office Assistant Preview File [Buy Office XP at Shop.Microsoft]
        File Used by Adobe Acrobat Paper Capture
  .ACQ  AcqURL File (bookmark manager)
  .ACR  American College of Radiology File
        Dicom  [XnView]
  .ACS  MS Agent Character File
  .ACT  MS Office Actor Program File [Buy Office XP at Shop.Microsoft]
        FoxPro Documenting Wizard Action Diagram
        Photoshop Color Table
        Action! Presentation
  .ACU  AppleLink-PE Compression Format (created by Floyd Zink; overtaken by Andy Nicholas' ShrinkIt; ShrinkIt should unpack)
        COBOL Intermediate Object File
  .ACV  OS/2 Audio Drivers
        Photoshop Saved Curve  Also see
  .ACW  MS Accessibility Wizard Settings
  .AD   AfterDark Screen Saver
        Ascend Password Protocol File
  .AD!  OzWin CompuServe E-mail/Forum Access QS-Special - Get Marked Online
  .AD2  2-bit Compressed Voice File
  .AD3  3-bit Compressed Voice File
  .ADA  ADA Program File
        ActiveDocs Answer Set
  .ADB  ADA Package Body
        HP Organizer Appointment Database
  .ADC  Chromeleon Demo Data File
        ActiveDocs Clipping Catalog
        Scanstudio 16-color Bitmap Graphic File
        Lingvo Dictionary Text File
  .ADD  OS/2 Adapter Device Driver
        Adobe Pagemaker File
        Advantage Database Server Data Dictionary
  .ADE  MS Access Project Extension [Buy Office XP at Shop.Microsoft]
        ADC Audio File
  .ADF  Adapter Description File
        Admin Config File
        Amiga Disk File (Uncompressed 901120 byte DD Diskimage) [Amiga Forever]
        Dog Creek QC Mask File
  .ADI  AutoCAD Plotter File
        Advantage Data Server Database Index File
  .ADJ  LISCAD Plus Adjustment File
  .ADL  QEMM MCA Adapter Description Library  [MCA]
        OzWin CompuServe E-mail/Forum Access QS-Special Get Marked
  .ADM  After Dark Screen Saver Module
        Windows Policy Template
        Addict Compiled Dictionary
        Advantage Data Server Database Memo File
  .ADN  1-2-3 Add-in Utility
        MS Access Blank Project Template [Buy Office XP at Shop.Microsoft]
  .ADO  Photoshop Duotone Options
        Stata Program
  .ADP  FaxWorks Modem Setup File
        Astound Dynamite File
        MS Access Project [Buy Office XP at Shop.Microsoft]
        AOLserver Dynamic Page File  [AOL]
  .ADR  After Dark Random Screen Saver Module
        Address Plus Database
        Smart Address Address Book
        Address Book
        Opera Web Browser Bookmark File
  .ADS  ADA Package Specification
  .ADT  HP NewWave Card Application Data File
        Advantage Data Server Database File
        Lingvo Dictionary File
        AdTech Fax File
  .ADV  GUS Virtual Device Driver
  .ADX  Lotus Approach Index File
        Archetype Designer Document
        Dynazip Active Delivery Script
        Sega Dreamcast Audio File [Source of files]
  .ADZ  GZ-Packed Amiga Disk File (see ADF) [Amiga Forever]
  .AE   SoftQuad Author/Editor File
  .AEH  iPer Advanced Embedded Hypertext
  .AEP  ArcExplorer Project File
  .AER  Adobe Atmosphere File  [As of Mar 2002 in beta]
  .AEU  MS AutoRoute Express Europe Route
  .AEX  PGP Armored Extracted Public Encryption Key  [PGP]
  .AF2  ABC Flowchart (Now Micrografx FlowCharter)
  .AF3  ABC Flowchart (Now Micrografx FlowCharter)
  .AFC  Apple Sound File
        ArisFlow Commander File
  .AFD  ArisFlow Diagram
        Prismo Graphics ActiveFile Data
  .AFF  AnyForm Form
  .AFI  Truevision Bitmap Graphic
  .AFL  Lotus Font
  .AFM  Outline Font Metric
        HP NewWave Cardfile Application
        LOUT File (High-Level Language For Document Formatting)
  .AFP  Flowchart Symbol Palette
        Papyrus Document Storage Format
        Prismo Graphics ActiveFile Proxy
        IBM Transactional Data Format (Advanced Function Print) (AS400 computer)
  .AFS  Filter Factory Photoshop Filter  [Added]
        Sega Dreamcast Compressed Audio
  .AFT  Flowchart Template
        AnyForm Template
  .AFW  Flowchart Work Area
  .AFX  Auto FX Photographic Edges (Photoshop add-in)
  .AG   Applix Graphic
        Argus Spreadsheet File
  .AG4  Access G4 File [Buy Office XP at Shop.Microsoft]
  .AGF  Atlas GeoFile
  .AGP  Aspen Graphics Pages
  .AGW  Aspen Graphics Windows
  .AHQ  AudioHQ Plugin Module
  .AHS  Photoshop Halftone Screens
  .AI   Adobe Illustrator Vector Graphic [XnView]
        Corel Trace Drawing
        Progress Database After Image File
        Advantage Database Server File
        EARS Component File (EARS = UK Liberal Democrats Election Agents Record System) [Filename starts with E]
  .AIF  Knowledgeware Setup Information
        Audio Interchange File  [IrfanView]
        SymbianOS Application Information File (set application properties)
  .AIFC  Audio Interchange File  [IrfanView]
  .AIFF  Audio Interchange File  [IrfanView]
  .AIH  ArcView Optional Index File (GIS-related file)
  .AIJ  Oracle After-Image Journal
  .AIL  AutoImager File (batch image conversion)
  .AIM  AOL Instant Messenger File  [AOL]
  .AIML  Artificial Intelligence Markup Language
  .AIN  AIN Compressed Archive
        ArcView Optional Index File (GIS-related file)
  .AINSO  VAX CRYSTALS Chemical Crystallogaphy File
  .AIO  APL File Transfer Format
  .AIP  Audiosoft Parameter File
  .AIQ  AzureIQ Client File (IT Audit Reporting)
  .AIR  Align It! Resource File
        Flight Simulator Aircraft Performance Info File [Free Flight Dynamic Editor]
  .AIS  Array of Intensity Samples (Graphic)
        Velvet Studio Instruments
        ACDSee Image Sequence File
  .AIX  HP NewWave Cardfile Application Data
  .AKF  Acrobat Key File
  .AKW  RoboHELP Help Project Index File
  .AL   Oracle File (used for networking)
  .ALA  Alan Adventure Language File
        Sharp Fax File (unverified)
  .ALB  JASC Image Commander Album
        Steinberg Cubase or VST Backup Song File
        Photo Soap2 File
  .ALBM  webAlbum Photo Album
         HP Photosmart Photo Printing Album
  .ALC  Norton Internet Security Ad Server File
        MP3 Embedded Dynamic Lyrics
  .ALE  Avid Log Exchange
  .ALF  Abacus Law File
        ALF Logic File ("Another logical framework"--structure editor for Martin-Löf's monomorphic type theory)
        AdventNet Look and  Feel Standards (ALFSTANDARDS.ALF)
        Aventail Connect License File (AVENTAIL.ALF)
        VPCom Remote User Configuration File
        LANDesk Client Manager Configuration File
        ACT! User Logon Tracking
        Color Quick Label
        Cadence Ambit BuildGates
  .ALI  SAP Proprietary Format Document File
        OM2 OMALI Native OMALI Document
  .ALIAS  Alias Image  [XnView]
  .ALL  Arts & Letters Symbols and Characters
        WordPerfect Printer Info
        Steinberg Cubase or VST Song File
        Always Working Page Format File
  .ALS  Alias Image [XnView]
        Calmira Shortcut File
  .ALT  WordPerfect Menu File
  .ALV  Photoshop Levels
        Aladdin Knowledge Systems Vbox Available Languages File (software distribution)
  .ALX  OM2 OMALI Plug-in Extension
  .ALZ  ALZip Compressed File (Korean site)
  .AM   Applix SHELF Macro
        Advantage Database Server File
  .AM2  AutoPlay Menu Studio Version 2
  .AM3  AutoPlay Menu Studio Version 3
  .AMB  Radiance Ambient File Format
  .AMC  Ant Movie Catalog
  .AMF  Advanced Module Format Music File
        DSMIA/Asylum Module Music
  .AMG  AMGC Compressed Archive (alternate site)
        AMG ACTOR System Image
  .AMI  Cocreate SolidDesigner Annotation File
        Amiga Paint  [XnView]
  .AML  AutoMage (Automation/Macro Software)
  .AMM  AMM File (pattern design pgm for Universal flat knitting machines)
  .AMP  Photoshop Arbitrary Map Settings
  .AMS  Extreme's Tracker Module Format
        Photoshop Monitor Setup
        Velvet Studio Module
  .AMZ  The Amazon Trail Saved Game
  .AN   Groundworks Text File
  .AN8  Anim8or 3D Animation
  .ANC  Canon Computer Pattern Maker File
  .ANF  AcuteNotes File (contains one or several notes order in a hierarchy)
  .ANI  Animated Cursor  Microangelo  [IrfanView]
  .ANL  Project Analyzer Saved Analysis
  .ANM  DeluxPaint Animation
  .ANN  Help Annotation
  .ANO  Annotation File (often used with annotating PDF files)
  .ANS  ANSI Graphic  [ANSI]
        MS Word Text and Layout [Buy Office XP at Shop.Microsoft]
  .ANSR  AnswerTool File
  .ANT  SimAnt for Windows Saved Game File
  .ANV  AirNav [XnView]
  .AOB  DVD Audio File (MPEG-2 program streams with additional info)
  .AOF  Acorn Object Format (used for data storage)
  .AOS  Nokia Add-on Software
  .AOT  ZenWorks Application Binary Object Template File
  .AP   Applix Presents File
        Datalex EntryPoint 90 Data File
        WHAP-Compressed Amiga Archive
  .APA  AlfaPad Organizer File
        ArcPad 6 Applet
  .APC  Lotus Printer Driver Characters
        Centura Team Developer Compiled Application File
  .APD  Lotus Printer Driver
        Centura Team Developer Dynamic Application Library File
  .APE  Music Format [Many different players]
  .APF  Lotus Printer Driver Fonts
        ArcPad 5 Profile
        Acrobat Profile File
        Homesite Project File
        Fax2000 File
  .API  Lotus Printer Driver Info
        Photoshop Ink Colors Setup
        Application Program Interface
        Acrobat Plug-in
        1st Reader Passed Parameter File
  .APIN  Adobe InDesign Import/Export Filter
  .APJ  Angel Debug Monitor Project File (link is PDF file)
        Music Screen Saver File (usually associated with .SCR file)
        ARM Project Manager File
  .APK  GameSpy Arcade Service
  .APL  Centura Team Developer Application Library File
        ArcPad 6 Layer
        APL Workspace File
  .APM  ArcPad 6 File
  .APO  Apollo Scripts
  .APP  R:Base, Symphony, DR-DOS, FoxPro (or other) Application
        Centura Team Developer Normal Mode Application File
        dBASE Application Object File
        ArcPad 5 Project
        SymbianOS Application
        CLARION for Windows Application
        Executable Application (under DR-DOS, NeXTstep, Atari)
  .APR  Lotus Approach 97 File
        ArcView Project File (GIS-related file)
        Employee Appraiser Performance Review File
  .APS  MS Visual C++ File
        ArcPad 5 Symbology File
        Advanced Patching Systems with Error Checking
  .APT  Centura Team Developer Text Mode Application File
        Lotus Approach Data View File
        Nimbus 7 SAMS Data File (a-priori temperature profiles)
  .APX  Lotus Approach Paradox-specific Information File
        Borland C++ Appexpert Database
        ArcPad 6 XML File
        Ability Photopaint Image [XnView]
  .AQ   Applix Data
  .AR   Compressed Archive File (used by MS Midtown Madness 1 & 2 games)
        Midtown Madness City Add-on
  .ARA  ATI Radeon Video Driver File
  .ARC  Archive File
  .ARCHIMEDES  Speccy Snapshot
  .ARF  Automatic Response File
  .ARH  ArHymo Hydrologic Simulation ()
  .ARI  Aristotle Audio File
        Compressed Archive
  .ARJ  Compressed Archive (Stuffit can expand)
  .ARK  Compressed Archive
  .ARL  AOL Organizer File  [AOL]
  .ARM  Armadillo Software Protection System
  .ARN  Astronomical Research Network  [XnView]
  .ARPX8  Techno Toys Arp-X8 MIDI Arpeggiator File
  .ARQ  Compressed Archive (often on a Macintosh)
  .ARR  Atari Cubase Arrangement
  .ARS  Artifax Report Editor (SQL query tool)
  .ART  Clip Art File
        Xara Studio Drawing
        Blood Archive  [Dragon UnPACKer]
        Duke Nukem 3D Archive  [Dragon UnPACKer]
        Canon Crayola Art File
        Another Ray Tracer Format
        AOL Johnson-Grace Compressed File  [AOL]
        First Publisher Raster Graphic
        PFS: Art Publisher  [XnView]
        Art Director Image  [XnView]
        Artisan  [XnView]
  .ARV  Arsiv File
        AutoRoute User Information
  .ARX  Compressed Archive
  .ARY  Compaq SmartStart Scripting Toolkit File
  .AS   Applix Spreadsheet
        Macromedia Flash Action Script (include files when writing large scripts)
  .AS3  Alternate Sources Data File [Warning: Link goes to a sexually-oriented site.]
        APL*PLUS II/386 and III/Windows Source Code
  .AS4  AS/400 Client Access
  .ASA  MS Visual InterDev File
        Active Server Document
  .ASC  ASCII Text File  [ASCII]
        PGP Armored Encrypted File  [PGP]
  .ASCX  Web User Control (part of MS .NET)
  .ASD  MS Word Automatic Backup [Buy Office XP at Shop.Microsoft]
        Lotus Screen Driver
        MS Advanced Streaming Format Description File
        Astound Presentation
  .ASE  Velvet Studio Sample
  .ASF  MS Active Streaming (Media) File (contains audio and/or video compressed with 3rd party codecs)
        Statgraphics Data
        Lotus Screen Font
        APL*Plus/PC APL Shared File
        Electronic Arts Music File
  .ASH  TASM Assembler Header
  .ASI  Borland Assembler Include
  .ASK  askSam Database
  .ASM  Assembler Source Language (various)
        Pro/Engineer Assembly File
  .ASMX  ASP.NET Webservices Source File
  .ASO  Assembler Object
        Astound Dynamite Objects
  .ASP  Active Server Page
        Procomm Plus ASPECT Program
        Astound Presentation File
        Photoshop Photo File Index
        Photoshop Separation Setup
        EROSION 3D Aspect File [Format (pdf)]
  .ASPI  Audio Catalyst
  .ASPX  ASP.NET Source File
  .ASR  Ms Automap Route
        Photoshop Scratch Area
  .ASS  Assembler/Disassembler 68HC11 File
        ASS I/O (programmers utility to pack multiple files into one file)
  .AST  Astound Multimedia File
        Photoshop Separation Tables
        Claris Works Assistant File
  .ASV  DataCAD Autosave File
        Photoshop Selective Color
  .ASX  Metafile (points to an .ASF structured file)
        Cheyenne Backup Script
        Video File
  .AT2  Aldus Persuasion 2.0 Auto Template
        DCX-AT200 Motion Control Command Language File
  .AT3  DCX-AT3000 Motion Control Command Language File
  .ATF  Photoshop Transfer Function
  .ATK  Bitmap Image (Andrew Toolkit Raster Object file) [XnView]
  .ATL  Hal/Supernova/Lunar/LunarPlus Screen Readers/Magnifiers
        PROGNOSIS Atlas Document File
  .ATM  Adobe Type Manager Data File
  .ATN  Adobe Photoshop Action File
  .ATO  Just Burn File (audio CD burner on Compaq computers)
  .ATR  Lightscape Material Library
  .ATS  Attityd Swedish Survey Program
  .ATT  AT&T Group 4 Bitmap (fax) [XnView]
  .ATW  AnyTime Deluxe PIM File  [PIM]
        Attityd Swedish Survey Program
  .ATX  A ZIP-formatted Compressed Archive (Use any ZIP program to open)
  .AU   Music File (various, usually Sun or UNIX)  [IrfanView]  [Linux Player]
  .AUD  Audio File used by Westwood Studios for various games
  .AUP  ePocrates File
  .AUT  AutoIt Script (automate any windows based task)
        PocketWear Car Lease Kit Vehicle Data File (Pocket PC)
        TLG Workplace CD Search File
        Xitami Webserver Admin Password File (default.aut)
        GPSMan-autoMapic File (moving-map real-time plotting)
        Signwave Auto-Illustrator File
        Descent Manager Mission File
        Authentication File (various)
        Interactive Pictures iPIX Format
  .AUX  TeX/LaTeX Auxilliary Reference File
        ChiWriter Auxilliary Dictionary File
  .AV   Final Draft AV Document File
  .AVA  Avagio Publication
  .AVB  Inoculan Anti-Virus Virus Infected File
        Avid Bins File
        Microsoft Chat Character File
  .AVC  Kaspersky Antivirus Toolkit File
  .AVD  Avery Label Pro Data File
  .AVI  Audio Video Interleave File  [IrfanView]
  .AVL  ArcView Theme Legend File (GIS-related file)
  .AVP  ArcView Pallet File (GIS-related file)
        Avid Project File
  .AVR  Audio Visual Research Sound File
  .AVS  Animation File
        Application Visualization System Format
        Stardent AVS X Image  [XnView]
        Winamp Advanced Visualization Studio File
        Avid Settings File
  .AVX  ArcView File (GIS-related file)
        Avid Extensions File
  .AW   HP AdvanceWrite Text File
        MS Answer Wizard File
        Applix Word File
  .AWB  Lavasoft Ad-aware Backup File
  .AWD  Faxviewer Document (AWD Microsoft Fax) [PolyView Viewer]
        Award BIOS File
        AWK Language Source Code File
  .AWE  Adobe Acrobat Bookmark XML File
  .AWF  Qui veut gagner des millions Archive  [Dragon UnPACKer]
        Who wants to be a millionaire Archive  [Dragon UnPACKer]
  .AWK  AWK Script
  .AWM  Animation Works Movie
  .AWR  Telsis Digital Audio File
  .AWS  StatGraphics Data File
  .AWX  MS DirectX 8.1
  .AX   DirectShow Filter
        DivX MPEG-4 DVD Filter [some filters work with Windows Media Player]
  .AXD  Avery Label Pro Re-Index File
  .AXE  Paradigm C++ Integrated Debugger File
        ChordMaster (Chord Chemistry and Sequencing program for guitarists)
        MS Autoroute Export File
  .AXG  MS Autoroute Trip File
  .AXL  ArcIMS XML Project File  [XML]
  .AXP  GraphStore eCADLite File
  .AXR  Telsis Digital Audio File
        ElcomSoft Advanced Archive Password Recovery
  .AXS  MindAvenue AXEL Stream File
  .AXT  ZenWorks snAPPshot ASCII Application Object Template
        Photoshop Replace Color/Color Range
  .AY   AY Chip Sound File (chip used in ZX spectrum and other arcade machines)
  .AZ   WinDVD File
  .AZZ  AZZ Cardfile Personal Information Manager