http://en.wikipedia.org/wiki/List_of_file_formats_%28alphabetical%29

0
	Compressed harddisk data 	DoubleSpace
0B
	Printer font with lineDraw extended character set 	PageMaker
001, 002, ...
	Split parts of a single whole file 	HJSplit
1
	Fax 	
1
	Fax 	many
1
	Roff/nroff/troff/groff source for manual page 	cawf2.zip
123
	Spreadsheet 	Lotus 1-2-3 version 9 - Lotus 1-2-3 version 97
15U
	Printer font with PI font set 	PageMaker
1ST
	Usually README.1ST text file 	
2GR
	286 Grabber File 	Win
301
	Fax 	Super FAX 2000 - Fax-Mail 96
386
	Intel 80386 processor driver 	Windows 3.x
386
	Windows virtual device driver 	Win
3DMF
	QuickDraw 3D Metafile 	QuickDraw
3DS
	3D Studio Graphics format 	3D Studio
3DT
	Database in which the meta-data of a 3D Topicscape is held 	3D Topicscape
3FX
	Effect 	CorelChart
3GR
	386 Grabber File 	Win
3GP
	Mobile Phone Video
3T4
	Binary file converter to ASCII 	Util3
4C$
	Datafile 	4Cast/2
4MD
	Musical file 	
4SW
	4DOS Swap File 	4DOS
4TH
	FORTH source code file 	ForthCMP - LMI Forth
555
	16 bit per pixel image file format (5bit per component) 	Sierra Entertainment
668
	Music (the mixing is always at 12048 Hz) 	
669
	Music (8 channels) 	The 669 Composer
6CM
	Music (6 Channel Module) 	Triton FastTracker
75
	75x75 dpi display font 	Ventura Publisher
7z
	7-Zipped file 	
8
	A86 assembler source code file 	
85
	85x85 dpi display font 	Ventura Publisher
8BF
	Adobe Photoshop compatibile filters/plugins
8CM
	Music (8 Channel Module) 	Triton FastTracker
8M
	Printer font with Math 8 extended character set 	PageMaker
8U
	Printer font with Roman 8 extended character set 	PageMaker
8xp
	Executable program for TI-83/84 Plus Graphics Calculator 	TI Connect
91
	91x91 dpi display font 	Ventura Publisher
96
	96x96 dpi display font 	Ventura Publisher
[edit] A
Ext. 	Description 	Used by
A
	ADA source code file 	
A
	Library 	unix
A##
	AlZip Compressed Files' pieces
A11
	Graphics AIIM image file 	
A80
	Assembler language source for 8080 	
AAC
	Advanced Audio Coding is a standardized, lossy compression and encoding scheme for digital audio. 	
AAF
	AutoPatcher file 	
AAF
	Advanced Authoring Format is an advanced media wrapper file for professional applications. 	
AAS
	Animation Play Script 	AAPlay
AB6
	Datafile 	ABStat
AB8
	Datafile 	ABStat
ABC
	Document 	ABC FlowCharter 1.0
ABP
	Data 	ABComp compressed
ABP
	AVS Barcode Profile 	AVS Barcode Source
ABF
	Adobe Binary Screen Font 	Adobe Systems Software
ABK
	Automatic backup file 	CorelDRAW
ABM
	Image PALS album file 	
ABM
	Album file (various programs)
ABR
	Adobe Brush file for PhotoShop 	PhotoShop
ABS
	Abstracts (info file) 	
ABS
	Data file 	Abscissa
AC
	Project backup 	Audit Command Language (ACL)
ACA
	Project 	Project Manager Workbench
ACB
	Archive 	ACB
ACB
	see ACMB 	
ACC
	Program (DR-DOS - ViewMax) 	GEM / resident
ACCDA
	Data 	Microsoft Access Database Wizard (Open XML)
ACCDB
	Data 	Microsoft Access Database (Open XML)
ACCDE
	Data 	Microsoft Access Database Wizard (Open XML)
ACCDT
	Data 	Microsoft Access Database Template (Open XML)
ACCDU
	Data 	Microsoft Access Database Wizard (Open XML)
ACE
	Archive 	ACE
ACF
	Adobe Custom Filter for PhotoShop 	PhotoShop
ACL
	Project 	Audit Command Language (ACL)
ACL
	AutoCorrect List 	Microsoft Office
ACM
	Audio Compression Module add-on 	Win
ACMB
	Graphics file 	
ACO
	Adobe Color Palette 	
ACT
	ACTOR source code file 	ACTOR
ACT
	Animations Works Actor (Graphics cell) 	Animation Works
ACT
	FoxDoc Action Diagrams 	FoxPro
ACT
	Presentation 	Action!
AD
	AfterDark screensaver module 	AfterDark
AD2
	ADPCM 2-bit compressed voice file 	ZFAX
AD3
	ADPCM 3-bit compressed voice file 	ZFAX
ADA
	Ada source code file 	
ADB
	Ada Package Body 	
ADC
	Bitmap graphics (16 colors) 	Scanstudio
ADC
	Dictionary 	Lingvo
ADD
	OS/2 adapter device driver 	
ADF
	Amiga Disk File 	unADF, UAE, WinUAE etc...
ADG
	Data 	ADG 3D Scene
ADI
	Graphics file 	AutoCAD
ADI
	Database Index File 	Advantage Database Server
ADICHT
	LabChart data acquisition file 	ADInstruments
ADL
	MCA adapter description library 	QEMM
ADM
	After Dark support file 	AfterDark
ADM
	ADEM file format 	ADEM
ADI
	Database Memo File 	Advantage Database Server
ADN
	Add-in 	Lotus 1-2-3
ADR
	After Dark support file 	AfterDark
ADS
	Ada Package Specification 	
ADT
	Datafile for cardfile application 	HP NewWave
ADT
	Dictionary 	Lingvo
ADT
	Fax 	AdTech
ADI
	Database Table 	Advantage Database Server
ADV
	GUS device driver 	Gf166.com
ADX
	Document 	Archetype Designer
ADZ
	Amiga Disk Zipped (See Amiga Disk File) 	GZip
AEP
	After Effects Project File 	Adobe After Effects
AF2
	Flowchart 	ABC FlowCharter 2.0
AF3
	Flowchart 	ABC FlowCharter 3.0
AFI
	Truevision bitmap graphics 	
AFL
	Font file (for Always) 	Lotus 1-2-3
AFM
	Datafile for cardfile application 	HP NewWave
AFM
	Type 1 font metric ASCII data for font installer 	ATM - many
AFP
	Shape palette 	ABC FlowCharter
AFT
	Template 	ABC FlowCharter 3.0
AFW
	Workplace 	ABC FlowCharter 3.0
AGR
	ArcView ASCII grid
AHK
	AutoHotkey script file 	AutoHotkey
AI
	Vector graphics file 	Adobe Illustrator
AIF
	see AIFF 	
AIFC
	Audio Interchange File Format with Compression 	
AIFF
	Audio Interchange File Format 	Convert (c) Villena
AiM
	Asm Text Mode Image File 	The Ultimate Draw
AIN
	Archive 	AIN
AIN
	Job schedule 	AutoIntern
AIO
	APL programming language file transfer format file 	
AIS
	Array of Intensity Samples graphics file 	Xerox
AIX
	Datafile for cardfile application 	HP NewWave
ALC
	Molecular coordinates 	Alchemy, RasMol
ALG
	Activity Log 	ARCSOLO
ALL
	Arts & Letters symbol and font files 	Arts & Letters
ALL
	Filelist w/ all files 	FRQView
ALL
	Format file for working pages 	Always
ALL
	General printer information 	WordPerfect for Win
ALO
	Almanac support file 	
ALT
	Menu file 	WordPerfect Library
ALZ
	AlZip Compressed Files
AMF
	Music (Advanced Module Format) 	DMP
AMG
	Archive 	AMGC
AMG
	System image file 	ACTOR
AML
	AutomationML 	AutomationML Group
AMR
	Audio format for mobile phones (Nokia, SonyEricsson)
AMS
	Adobe Monitor Setup calibration file 	PhotoShop
AMS
	Music format 	
ANI
	Animation cursors for Win 	Win95 - WinNT
ANI
	Animation 	IconAuthor
ANM
	Animation 	Deluxe Paint Animator
ANN
	Help Annotations 	Windows 3.x
Ann
	Multi volume ARJ archive 	ARJ
ANS
	ANSI character graphics (animation) file 	ANSView
ANS
	ASCII text ANSI character set 	NewWave Write
AOL
	America On-line for Windows DLL 	Win
AOS
	Add-On Software 	Nokia 9000
AP
	Archive 	WHAP
AP
	Datafile 	Datalex EntryPoint 90
APC
	Printer driver 	Lotus 1-2-3
APD
	Printer driver 	Lotus 1-2-3
APE
	Monkey's Audio (Lossless) 	audio media players
APF
	Printer driver 	Lotus 1-2-3
API
	Adobe Printer Ink file for PhotoShop 	PhotoShop
API
	Passed parameter file 	1st Reader
API
	Printer driver 	Lotus 1-2-3
APL
	APL work space format file 	
APL
	Support module used by Manugraphics APL products 	
APM
	Authorware Macintosh 	Authorware
APP
	Add-in application file 	Symphony
APP
	Application object file 	dBASE Application Generator
APP
	Application 	FoxPro
APP
	Application and Application Bundle 	Mac OS X
APP
	Executable workflow / macro file 	Automator
APP
	Executable application file 	DR-DOS - NeXTstep - Atari
APP
	Generated application 	FoxPro
APR
	Employee performance review 	Employee Appraiser
APW
	Authorware Windows 	Authorware
APX
	Appexpert database file 	Borland C++ 4.5
AR
	Argon - for 3D Modeling 	Ashlar-Vellum
AR7
	Archive 	AR7
ARC
	Archive 	ARC - PKARC/PKXARC - PKPAS - PKUNPAK - QUARK
ARC
	Archive 	SQUASH
ARD
	Map 	Holux - Alan
ARF
	Automatic Response File 	
ARH
	Archivers definitions file 	DN
ARI
	Archive 	ARI
ARJ
	Archive 	ARJ - ARJZ
ARK
	ARC archive 	CP/M port of ARC file archiver
ARK
	Archive 	QUARK
ARK
	Managing your Money Archive File 	
ARR
	Arrangement 	Atari Cubase
ART
	Gerber artwork 	Cadence Allegro
ART
	First Publisher, Designworks, Greenstreet Draw graphic file 	All GST/Greenstreet Draw products
ART
	Graphics (scrapbook) 	Art Import
ART
	Graphics format (Another Ray Tracer) 	PFS:1st publisher - Art Import
ARX
	Archive 	ARX
ASC
	ASCII text file 	
ASC
	Transport armor file 	PGP
ASD
	Autosave file 	Microsoft Word
ASD
	Presentation 	Astound
ASD
	Screen driver 	Lotus 1-2-3
ASE
	Velvet Studio Sample 	AWAVE
ASE
	ASCII Scene Export 	3D Studio
ASF
	Datafile 	STATGRAPHICS
ASF
	Screen font 	Lotus 1-2-3
ASF
	Advanced Streaming Format (Compressed Windows audio/video) 	Microsoft Corporation
ASK
	SYSGEN answer file 	RT-11
ASH
	Assembly language header file 	TASM 3.0
ASI
	ASIC language source 	ASIC
ASI
	Assembler include file 	Turbo C - Borland C++
ASM
	Assembler language source 	TASM, MASM, NASM, Yasm, FASM
ASMX
	ASP.NET Web Service 	Microsoft Corporation
ASO
	Assembler object (object-oriented) file 	Turbo Assembler
ASP
	ASPECT source code file 	Procomm Plus
ASP
	Association of Shareware Professionals OMBUDSMN.ASP notice 	
ASP
	Active Server Pages of Microsoft.Net 	Microsoft Corporation
ASPX
	ActiveX Server Pages of Microsoft.Net 	Microsoft Corporation
ASS
	Amalgam Scene Specification 	Halo 2 Map Editor
ASS
	Advanced SubStation Alpha (Subtitles) 	
AST
	Adobe Color Separation table for PhotoShop 	PhotoShop
ASW
	Authorware Star 	Authorware
ASX
	Advanced Stream Redirector file, redirects to an ASF file (see ASF) 	Microsoft Corporation
ASZ
	Skin 	AltDesk
AT2
	Auto template 	Aldus Persuasion 2.0
AT3
	Atrac 3 Sound/music file 	All Sony devices and programs with the Atrac 3+ specification
ATM
	Adobe Type Manager data/info 	
ATN
	Adobe Photoshop action 	Adobe Photoshop
ATT
	AT&T Group 	GCGW
ATY
	Produced when an association type is exported by 3D Topicscape 	3D Topicscape
AU
	Sun/NeXT/DEC Audio file 	AWAVE, GoldWave
AU
	Sound (audio) file 	Sun Microsystems - Convert (c) Villena
AUD
	Audio file 	AudioRack
AUP
	Audacity project file 	Audacity
AUX
	Auxiliary dictionary 	ChiWriter
AUX
	Auxiliary references 	TeX/LaTeX
AUZ
	Ableton Live File 	Authorization File for Ableton Live
AVA
	Publication 	Avagio
AVB
	AntiViral Toolkit Pro Bases 	
AVI
	Audio Video Interleaved animation file 	Video for Windows
AVR
	Audio Visual Research 	AWAVE
AVS
	Application Visualization System 	
AVT
	AVATAR-coding files 	A3E
AW
	Text file 	HP AdvanceWrite
AWA
	Animations Works Accelerated Movie 	Animation Works
AWD
	Microsoft Fax At Work Document 	Microsoft Fax At Work
AWK
	AWK script/program 	
AWM
	Animations Works Movie (as .AVI) 	Animation Works
AWS
	Data 	STATGRAPHICS
Ax
	Directshow filter file format 	
AXF
	ARM Executable Image generated by the ARM tools. 	
AXM
	Axmedis object 	Axmedis Tools
AZD
	Amazon Software Download 	Amazon Software Download
AZW
	DRM enabled eBook 	Amazon Kindle
AZZ
	Data file 	AZZ Cardfile
[edit] B
Ext. 	Description 	Used by
B&W
	Black and white graphics file 	atari - mac
B&W
	Mono binary screen image 	1st Reader
B
	Batch list 	APPLAUSE
B_W
	Black and white graphics file 	atari - mac
B1N
	Both mono and color binary screen image 	1st Reader
B30
	Printer font (JLaser - Cordata) 	Ventura Publisher
B8
	Raw graphics file (one byte per pixel) plane two 	PicLab
BA
	Binary Archive 	Scifer Archiver and Compression [External Header Mode]
BAC
	Compiled BASIC 	RT-11 BASIC-11
BAD
	Bad file 	Oracle - many
BAD
	File which covers bad blocks on disk volume (not to be moved) 	RT-11
BAK
	Backup file 	
BAL
	Music score 	Ballade
BALANCE
	Balance accounting sheet file 	Balance
BAR
	Horizontal bar menu object file 	dBASE Application Generator
BAR
	Info Bar for GFX2EXE 	GFX2EXE
BAS
	BASIC language source 	QuickBASIC - GW-BASIC - FreeBASIC
BAT
	Batch file 	MS-DOS, RT-11
BB
	Database backup 	Papyrus
BBL
	Bibliographic reference file 	TeX/BibTeX
BBM
	Brush 	Deluxe Paint
BBP
	Playlist 	BassBox
BBS
	Bulletin Board System announce or text info file 	
BBS
	Hudson-style messagebase 	FTN software
BC!
	Unfinished download 	Unfinished BitComet download (a BitTorrent client)
BCF
	Card data 	Bingo Card Creator
BCH
	Batch process object file 	dBASE Application Generator
BCH
	Datafile 	Datalex EntryPoint 90
BCO
	Outline font description 	Bitstream
BCP
	Borland C++ makefile 	
BCT
	Backup dictionary 	Clarion
BCW
	Environment settings 	Borland C++ 4.5
BDB
	Bookends database 	Bookends
BDC
	Dictionary 	Lingvo
BDEF
	Builder Definition 	Websphere Portlet Factory
BDF
	Adobe Glyph Bitmap Distribution Format 	Adobe Software
BDF
	Binary update file 	BUPDATE.EXE (c) TNT Techn.
BDF
	Bitmap Distribution Format font file 	X11
BDF
	Datafile 	Egret
BDM
	Videoclip 	AVCHD
BDR
	Border 	Microsoft Publisher
BDT
	Dictionary 	Lingvo
BEZ
	Outline font description 	Bitstream
BF
	Brainfuck sourcefile 	
BF2
	Bradford 2 font 	
BFC
	Briefcase Win95 	Win95
BFM
	Font metrics 	unix/Frame
BFX
	Fax 	BitFax
BGA
	Bitmap graphics 	
BGI
	Borland Graphics Interface device driver 	Turbo C - Turbo Pascal
BI
	BASIC include file 	Visual Basic - FreeBASIC
BIB
	Bibliography (ASCII) 	
BIB
	Database - not compatible with TeX format 	Papyrus
BIB
	Literature database 	TeX/BibTeX
BIF
	Binary Image Format b&w graphics file 	Image Capture board
BIK
	Bink video file (RAD Video)
BIN
	Binary file, usually zero-start (.com analog) 	
BIN
	SGI Powerflip 	
BIN
	Text mode memory dump 	The Draw - TUD - ACiDDraw - etc
BIO
	BioniX Wallpaper playlist file 	BioniX Wallpaper Changer
BIO
	OS/2 BIOS 	
BIT
	Bitmap X11 	
BK!
	Document backup 	WordPerfect for Win
BK
	Faxbook 	JetFax
BK?
	Backup file 	
BKn
	Timed backup file for document window n 	WordPerfect for Win
BKP
	Backup file 	Write - TurboVidion DialogDesigner
BKW
	Mirror image of font set 	FontEdit
BLD
	BLoaDable picture 	BASIC
BLD
	SYSGEN Build procedure file 	RT-11
BLEND
	Blender3D Project File 	Blender
BLG
	Backup Log 	ARCSOLO
BLK
	Temporary file 	WordPerfect for Win
BM
	BitMap graphics file 	
BM3
	UIQ3 Phone backup 	
BMK
	Help Bookmarks 	Windows 3.x
BMP
	OS/2 or Win graphics format (BitMap Picture) 	QPeg - CorelDraw - PC Paintbrush - many
BMT
	Ami Pro Button 	Ami Pro
BNA
	Data 	Atlas Boundary
BNK
	Adlib instrument bank file 	
BNR
	Graphics Banner 	Banner - Poster
BOK
	Shamela Library book 	Shamela Library Program
BOO
	Book-format 	READIBM
BOO
	Compressed file ASCII archive created by BOO (msbooasm.arc) 	msbooasm.arc
BOO
	Boo programming language source file. 	Boo Programming Language
BOT
	Bot files, these go with JKB files 	Quake 3 Engine
BPC
	Chart 	Business Plan Toolkit
BPOLY
	Data 	Prisms binary 3D object
BPP
	Backup application 	Clarion
BPT
	Bitmap fills file 	CorelDRAW
BR
	Script 	Bridge
BRD
	Eagle Layout File 	
BRD
	Tanzzle board file 	Tanzzle
BRD
	Cadence Allegro board file 	Cadence
BRK
	Fax 	Brooktrout Fax-Mail
BRK
	The Brake! Mailer REXX script 	The Brake!
BRL
	CAD 	Ballistic Research Laboratory CAD
BS2
	Archive 	BS2.EXE
BSA
	Archive 	BSArc
BSC
	Compressed Apple II file archive created by BINSCII 	BINSCII
BSC
	Database 	Source Browser
BSC
	Pwbrmake object file 	Microsoft Fortran
BSP
	Half-Life\Half-Life 2 map files 	Valve Corporation
BSS
	Casio Phone base 	PC-LINK
BST
	BiblioTex file (BiblioTex=bibliography file) 	TeX
BSY
	Busy flag 	FTN soft
BTM
	Batch-to-memory (quick batch) 	4dos -ndos
BTN
	Makeover Button file 	
BUFR
	Binary Universal Form for the Representation of Meteorological Data
BUG
	Bugs and Problems 	
BUN
	LucasArts Bundle File 	
BUP
	Backup file 	
BUT
	Button definitions 	Buttons!
BUY
	Datafile format 	movie
BVn
	Overflow file below insert point in Doc n 	WordPerfect for Win
BWB
	Spreadsheet application 	Visual Baler
BWR
	Beware (buglist) 	Kermit
BYU
	BYU Movie 	BYU
BZ2
	Archive 	bzip2
BZM
	Map 	Blitzkrieg
[edit] C
Ext. 	Description 	Used by
C--
	C\u2014language source 	Sphinx C--
C
	C language source 	Watcom C/C++
C
	Unix file archive 	COMPACT
C++
	C++ language source 	
C00
	Print file 	Ventura Publisher
C01
	Typhoon wave files 	AWAVE
C86
	C source code file 	Computer Innovation C86
CA
	Initial cache data for root domain servers 	Telnet
CA?
	Borland packed and split file 	Borland Installer
CAB
	Win 95 packed file 	Win 95
CAC
	dBASE IV executable when caching on/off (see cachedb.bat) 	
CAD
	Drawing 	BobCAD-CAM
CAD
	Document 	Drafix Windows CAD
CAL
	Calendar file 	Windows 3.x
CAL
	Spreadsheet format 	SuperCalc
CALS
	Computer Aided Acquisition and Logistics 	
CALS
	Support Raster Format 	
CAM
	Casio Camera 	
CAN
	Fax 	Navigator Fax
CAP
	Caption 	Ventura Publisher
CAP
	Capture file 	ProComm - Telix
CAS
	C + ASM language source 	Turbo C
CAT
	Catalog 	CP Backup - dBASE IV
CAT
	Device driver digital signature 	Microsoft Windows
CAT
	Stellarium Star Catalogue 	Stellarium
CATS
	Combined source 	ATS
CBA
	Source code 	Creative BASIC
CBC
	Fuzzy logic system 	CubiCalc
CBL
	COBOL source code file 	
CBM
	Compiled bitmap graphics 	XLib
CBR
	Comic Book Reader (RAR file) 	CDisplay and similar
CBS
	MasterWord button bar configuration file 	
CBT
	Computer Based Training 	many
CBZ
	Comic Book Reader (ZIP file) 	CDisplay and similar
CC
	C++ source code file 	
CC
	CC language source 	CC
CCC
	Bitmap graphics (native format) 	Curtain Call
CCF
	Communications configuration file 	Symphony
CCH
	Chart 	CorelChart
CCITT
	CCITT Group 3 and Group 4 Encoding 	
CCL
	Communication Command Language file 	Intalk
CCO
	BTX Graphics file 	XBTX
CCT
	Print Template 	BobCAD-CAM
CD
	CD description 	DN
CDA
	CD-Audio 	Win95
CDB
	Card database 	CardScan
CDB
	Main database 	TCU Turbo C Utilities
CDF
	Common Data Format 	
CDF
	Cyberspace Description Format 	
CDF
	Graphics 	netcdf
CDK
	Document 	Atari Calamus
CDL
	CADKey CADL Language 	CADKey
CDM
	Disk Drivers NPA 	Novell NetWare
CDM
	Music format (compressed) 	
CDR
	Vector graphics format (drawing) 	CorelDraw!
CDT
	Corel Draw Template File 	CorelDraw!
CDX
	Compound index file 	Visual FoxPro, Advantage Database Server
CE
	Computer Eyes 	Conversion Artist
CE
	Main.ce 	The FarSide Computer Calendar
CEB
	Cont. Edge Bitmap 	Conversion Artist
CEF
	CA-Clipper Workbench Application 	CA Clipper
CEF
	Export File 	
CEF
	Compact Embedded Font 	Adobe Illustrator
CEG
	Bitmap graphics 	Tempra Show - Edsun Continuous Edge Graphics
CEL
	Animation CEL 	3D Studio
CEL
	Graphics 	Autodesk Animator - Lumena
CF
	Configuration file 	imake
CFG
	Configuration file 	
CFL
	Chart 	CorelFLOW
CFM
	ColdFusion Markup Language 	Adobe ColdFusion
CFN
	Font data 	Atari Calamus
CFO
	C Form Object internal format object file 	TCU Turbo C Utilities
CFP
	Fax 	The Complete Fax Portable
CFT
	CFast graphics file 	Disney Animation Studio
CGA
	CGA display font 	Ventura Publisher
CGI
	Common Gateway Interface script 	
CGM
	Computer Graphics Metafile vector graphics 	A&L - HG - many
CH
	Clipper language header 	CA Clipper
CH3
	Chart 	Harvard Graphics 3.0
CH4
	Presentation 	Charisma 4.0
CHD
	Font descriptor 	FontChameleon
CHI
	ChiWriter Document 	ChiWriter - Chiview
CHK
	Recovered data 	DOS CHKDSK
CHK
	Temporary file 	WordPerfect for Win
CHL
	Configuration History Log 	
CHM
	Compiled Help File 	Microsoft Windows, Help Explorer Viewer
CHN
	Data 	Ethnograph 3
CHP
	Chapter file 	Ventura Publisher
CHR
	Character set 	Turbo C - Turbo Pascal
CHT
	Chart 	Harvard Graphics 2.0 - SoftCraft Presenter
CHT
	CHeaT in any program/game 	many
CHT
	Interface file for ChartMaster 	dBASE
CHZ
	Archive 	CHARC
CIF
	Caltech Intermediate Format graphics file 	
CIF
	Chapter information 	Ventura Publisher
CIF
	Crystallographic Information File 	RasMol, Jmol
CiM
	C Text Mode Image File 	The Ultimate Draw
CIX
	Database index 	TCU Turbo C Utilities
CKB
	Borland C++ 4.x editor keystroke mapping 	BCW.EXE
CL
	COMMON LISP source code file 	
CLA
	Source 	Clarion
CLASS
	Java class file 	Java
CLD
	Clipper debugger configuration file 	CA Clipper
CLP
	Clip art graphics file 	Quattro Pro
CLP
	Clipboard file 	Windows 3.x
CLP
	Compiler response file 	CA Clipper
CLP
	Graphics format 	PCPAINT/Pictor
CLR
	Color binary screen image 	1st Reader
CLR
	Color definitions 	Photostyler
CLR
	Color scheme 	Boxer/2
CLR
	Palette file for GIS format 	
CLS
	C++ class definition file 	
CLW
	MFC Class Wizard information 	Microsoft VC++
CM
	Data file 	CraftMan
CMB
	Xtree for Windows Button Bar file 	
CMD
	Command 	dBASE - Waffle
CMD
	Command Prompt batch file 	Microsoft Windows NT based operating systems
CMD
	executable programs 	CP/M-86 operating system
CMD
	External command menu 	1st Reader
CMD
	OS/2 batch/REXX file 	OS/2
CMF
	FM-music file (Creative Music File) 	
CMK
	Card 	Card Shop Plus
CMM
	CMM script (batch) file 	CEnvi
CMP
	Bitmap graphics (Lead CMP compression) 	
CMP
	Compressed data 	PKWare Inc. data compression library
CMP
	Header file for PostScript printer files 	CorelDRAW
CMP
	Photofinish Calibration Map 	Photofinish
CMP
	User dictionary 	Microsoft Word for DOS
CMRL
	Concise message routing language 	DOTGO
CMS
	Content Management System 	Any Web Browser
CMU
	Carnegie Mellon University Formats 	
CMV
	Animation (CorelMove CorelDraw 4.0) 	CorelMove CorelDraw 4.0
CNC
	CNC general program data 	
CND
	System generation conditional file 	RT-11
CNF
	Configuration (program - printer setup) 	program - printer setup
CNF
	Configuration file 	
CNV
	Temporary file 	WordPerfect for Win
CNV
	Winword DLL used as part of an import operation (CNV=converter) 	Microsoft Word
CO
	Cobalt - parametric drafting and 3D modeling 	Ashlar-Vellum
COB
	Calgari trueSpace2 File Format 	
COB
	COBOL source code file 	
COD
	Code definition table 	UUPC
COD
	Datafile 	Forecast Plus - Microsoft Multiplan - StatPac Gold
COD
	file uncluding CODES for any program/game 	many
COD
	Printer code definition file 	Boxer/2
COD
	Program compiled code 	FORTRAN
COD
	Template source file 	dBASE Application Generator
COD
	Videotext file 	
COE
	Coefficient file 	Xilinx ISE
COF
	Animation Control File 	Diablo II
COL
	Color palette 	Autodesk Animator - many
COL
	Spreadsheet 	Microsoft Multiplan
COM
	Command (memory image of executable program) 	DOS
COM
	Indirect command file (sequence of commands to be executed) 	RT-11
CON
	Configuration file 	Simdir
CON
	MSTS Consist file 	MSTS
CPC
	Compressed image 	Cartesian Perceptual Compression
CPD
	Script 	Complaints Desk
CPF
	Fax 	The Complete Fax
CPI
	ColorLab Processed Image bitmapped graphics file 	
CPI
	MS-DOS codepage file 	MODE.EXE
CPL
	Control panel file 	Windows 3.x
CPL
	Presentation 	Compel
CPMZ
	ConPro/Miradi Zipfile 	Miradi and ConPro
CPP
	C++ language source 	Watcom C/C++
CPP
	Presentation 	CA-Cricket Presents
CPR
	Knowledge Access 	GCGW
CPS
	backup of startup files by QEMM (?) autoexec.cps 	
CPT
	Encrypted memo file 	dBASE
CPT
	Mac file archive 	COMPACT PRO
CPT
	Template 	CA-Cricket Presents
CPZ
	Music text file 	COMPOZ
CR2
	RAW image format 	Canon digital cameras
CRA
	Advanced crack file (usually text) 	
CRD
	Cardfile 	Windows 3.x - YourWay
CRD
	Map 	Holux - Alan
CRD
	Molecular coordinates 	CHARMM, RasMol
CRF
	Cross-reference 	Microsoft MASM - Zortech C++, RT-11 CREF
CRK
	Crack file (usually text) 	
CRP
	Encrypted database 	dBASE IV
CRS
	File Conversion Resource 	WordPerfect 5.1
CRT
	Terminal settings information 	Oracle
CRU
	Compressed file archive created by CRUSH 	
CS
	C# source file 	C#
CSG
	Batch file (Submit) 	ISIS/w
CSG
	Graph 	Statistica/w
CSM
	Borland C++ 4.x precompiled header file 	BCW.EXE
CSP
	PC Emcee Screen Image file 	Computer Support Corporation
CSS
	Datafile 	CSS - Stats+
CSS
	Datasheet 	Statistica/w
CSS
	cascading style sheet 	
CSV
	Adjusted EGA/VGA palette 	CompuShow
CSV
	Comma Separated Values text file format (ASCII) 	
CTC
	Control file 	PC Installer
CTF
	Character code translation file 	Symphony
CTK
	CommonTime Key file 	CommonTime software applications
CTL
	Control file 	dBASE IV - Aldus Setup
CTL
	BATCH control file (generated by BATCH from .BAT file) 	RT-11
CTT
	BATCH Temporary file 	RT-11
CTX
	Ciphertext file 	Pretty Good Privacy RSA System
CTX
	Course TeXt file 	some Microsoft online guides
CTX
	document 	Creativyst Table eXchange
CUF
	C Utilities Form definition 	TCU Turbo C Utilities
CUR
	Windows resource (cursor image file) 	Resource Workshop - WRT - Watcom Resource Editor
CUT
	Graphics format (bitmapped graphics) 	dr. Halo
CV4
	Color file 	CodeView
CVP
	Cover page 	WinFax
CVS
	Graphics 	Canvas
CVT
	Backup file for CONVERTed database file 	dBASE IV
CVW
	Color file 	CodeView
CWEB
	C Web 	
CWK
	Datafile 	ClarisWorks, Appleworks
CXX
	C++ source code file 	Zortech C++
[edit] D
Ext. 	Description 	Used by
D
	D Programming Language source file 	DMD
D4D
	Data 	Draw 4D object
D4P
	Data 	Draw 4D Pro object
D64
	Commodore 64 disk image
DAA
	Direct Access Archive 	
DAF
	Data file 	Digital Anchor
DAT
	Document 	Microsoft Word Format (old)
DAT
	data 	RSNetWorx Project
DAT
	Data file in special format or ASCII 	
DAT
	Database file 	Clarion (programming language)
DATS
	Dynamic source 	ATS
DB$
	Temperature debug info 	Clarion Modula-2
DB$
	Temporary file 	dBASE
DB
	Database file 	Paradox - XTreeGold - dbvista
DB
	Configuration 	dBASE IV - dBFast
DB
	Multi Edit config 	ME
DB2
	Database 	dBASE II
DB3
	Database 	dBASE III
DBA
	Database file 	Turbo Prolog - DataEase
DBA
	DarkBasic source code
DBC
	DataBaseContainer 	Visual FoxPro
DBD
	Business data 	Business Insight
DBD
	Debug info 	Clarion Modula-2
DBF
	Database file 	dBASE III/IV - Visual FoxPro - dBFast - DataBoss - DBVista - CA-Clipper - Visual Objects - Alaska Xbase++ -

Advantage Database Server
DBG
	Debugger script 	DOS debug - Watcom debugger
DBG
	Symbolic debugging information 	Microsoft C/C++
DBK
	Database backup 	dBASE IV
DBL
	DIBOL source file 	
DBM
	Datafile 	DataEase
DBM
	Menu template 	DataBoss
DBO
	Compiled program 	dBASE IV
DBPro
	DarkBasicPro Project
DBS
	Data file used by Managing Your Money 	
DBS
	Database in SQL Windows format 	
DBS
	Datafile 	PRODAS
DBS
	Printer description file 	Microsoft Word, Microsoft Works
DBT
	FoxBASE+ style memo 	FoxPro 2.x
DBT
	Memo file for database w/same name 	dBASE IV - dBFast
DBW
	Windows file 	DataBoss
DBX
	DataBeam 	GCGW
DBX
	AutoCAD Database 	AutoCAD
DBX
	Archive File 	Outlook Express
DC6
	Image file 	Diablo II
DCA
	Document Content Architecture text file 	IBM DisplayWrite
DCC
	Animation 	Diablo II
DCF
	floppy disk image 	Disk Copy Fast
DCL
	Delphi Control Library 	Borland Delphi
DCM
	DCM music module 	AWAVE
DCP
	OS/2 device code page 	OS/2
DCS
	Bitmap graphics (CYMK format) 	QuarkXPress
DCS
	Datafile 	ACT! Activity Files
DCT
	Dictionary: used by many programs with program dependent format 	Clarion
DCT
	Spell checking dictionary 	Harvard Graphics 3.0 - Symphony
DCT
	DataBaseContainer Extension 	Visual FoxPro
DCU
	Delphi unit (compiled) 	Borland Delphi
DCW
	Walter Machine Programing 	Walter Profile Editor
DCX
	Multi-page PCX graphics (common fax format) 	Intel - SpectraFAX
DCX
	DataBaseContainer Index 	Visual FoxPro
DD
	Macintosh file archive 	DISKDOUBLER
DDA
	Data 	GLBasic ASCII 3D object
DDB
	Bitmap graphics 	
DDB
	Digidesign Database File 	Digidesign ProTools
DDI
	Disk image 	DiskDupe
DDP
	Device Driver Profile file 	OS/2
DDS
	DirectDraw Surface file 	Microsoft Flight Simulator, other Microsoft programs
DEB
	DEBUG script 	DOS Debug
DEF
	Assembly header file 	Geoworks
DEF
	Defaults - definitions 	
DEF
	Linker definition file 	TLink - WLink...
DEM
	Demonstration 	
DEM
	Digital Elevation Model 	
DEM
	Graphics file 	VistaPro
DEM
	Vista DEM file 	Meta.exe VP3
DES
	Ascii text parameter description 	AWAVE
desktop
	Desktop Entry 	freedesktop.org
DEV
	Device driver 	
DEV
	SYSGEN handler build procedure 	RT-11
DEV
	Dev-C++ project file 	Dev-C++
DFD
	Data Flow Diagram graphic file 	Prosa
DFI
	Outline font description 	Digifont
DFL
	Default program settings 	Signature
DFM
	Data Flow Diagram model file 	Prosa
DFM
	Delphi form module 	Borland Delphi
DFS
	Delight Sound File 	
DFV
	Printing form (Word) 	Microsoft Word
DFX
	Micrografx Effects DLL 	
DGN
	Graphics file 	MicroStation
DGS
	Diagnostics 	
DH
	Dependency information for .ph 	Geoworks
DHP
	Dr. Halo PIC Format graphics file 	Dr. Halo II - III
DHT
	Datafile 	Gauss
DI
	D Programming Language interface file 	DMD
DIA
	Diagraph graphics file 	Computer Support Corporation
DIB
	Device Independent Bitmap 	rarely used Windows 3.0 bitmap; Win - OS/2
DIC
	Dictionary (e.g. from WinWord) 	
DIF
	Borland patch data file 	Borland patch
DIF
	Data Interchange Format 	Visicalc
DIF
	OS/2 V2.2 Display Information File 	OS/2
DIF
	Output from Diff command - script for Patch command 	
DIF
	SRCCOM, BINCOM output file 	RT-11
DIG
	Digilink 	AWAVE
DIG
	Sound Designer 1 audio file 	AWAVE
DIP
	Graphics 	
DIP
	Watcom debug info processor 	WatcomDebugger
DIR
	Dialing directory file 	Procomm Plus
DIR
	Directory file 	VAX - CPS Backup
DIR
	Movie 	MacroMind Director 4.x
DIR
	Directory listing file 	RT-11
DIS
	Distribution file 	VAX Mail
DIS
	Thesaurus 	CorelDraw
DIZ
	Description file (Description In Zip) 	
DJVU
	A PDF LIKE FILE 	DJVU
DKB
	Raytraced graphics 	DKBTrace
DL
	Animation format (Italian origin) 	Display - DL Viewer
DLD
		Lotus 1-2-3
DLG
	Dialog resource script file 	Microsoft Windows SDK
DLG
	Dialog resources 	DN
DLF
	Dialogue Live Format 	Produced by Exstream Dialogue and edited by Dialogue Live Editor
DLG
	Windows SDK dialog editor data file
DLG
	Windows SDK dialog editor data file 	
DLL
	Dynamic-link library 	Windows 3.x - OS/2
DLL
	Export/import filter 	CorelDRAW
DLM
	Microsoft File Transfer Manager 	Microsoft File Transfer Manager
DLP
	Data 	DAQLab
DLS
	Setup 	Norton Disklock
DMF
	Music format (Delusion Digital Music File) 	Delusion
DMG
	Apple Disk Image 	Mac OS X (Disk Utility),
DMO
	Demo 	Derive
DMP
	Dump file (eg. screen or memory) 	
DMP
	DUMP utility output file 	RT-11
DMS
	Amiga file archive 	DISKMASHER
DNG
	Digital Negative (DNG), a publicly available archival format for the raw files generated by digital cameras. 	At least 30 camera models from at least 10 manufacturers, and at least 200 software products.
DNT
	data 	RSNetWorx Project
DOC
	A Document, or an ASCII text file with text formatting codes in with the text. This generic extension is used by many word processors. 	Microsoft Word and others
DOCM
	Microsoft Word 2007 Master document 	Microsoft Word 2007
DOCX
	Office Open XML Text document 	Microsoft Word
DOF
	Delphi project options file 	Borland Delphi
DOG
	Screen file 	Laughing Dog Screen Maker
DOH
	Dependency information for .poh 	Geoworks
DOR
	Roland Digital audio file 	Roland
DOS
	External command file 	1st Reader
DOS
	Network driver (eg. pkt_dis.dos) 	
DOS
	OS/2 V3 SVGA PMI-File 	Svga.exe
DOS
	Something for MS-DOS (e.g. msdos.dos) 	Win95
DOS
	Text file containing DOS specific info 	
DOT
	Line-type definition file 	CorelDRAW
DOT
	Microsoft Word document template 	Microsoft Word
DOTX
	Office Open XML Text document template 	Microsoft Word
DOX
	Text file 	MultiMate 4.0
DOZ
	Description Out of Zip 	VENDINFO
DP
	Calendar file 	Daily Planner
DP
	Data file 	DataPhile
DPR
	Default project- and state-related information 	Borland C++ - Delphi - C
DPX
	Digital Moving Picture Exchange 	
DRP
	Web3D File 	Web3D
DRS
	Display Resource 	WordPerfect for Win
DRV
	Driver 	
DRW
	Designer vector graphics file 	Designer - MicroGraphix
DS
	TWAIN Data Source 	Any twain-source must supply one xxx.ds file
DS1
	Map file 	Diablo II
DS4
	Vector graphics 	Micrografx Designer 4.x
DSC
	Celestia Deep Space Catalog file 	Celestia
DSC
	Description file 	
DSC
	Discard file 	Oracle
DSD
	Database 	DataShaper
DSF
	Data Storage Format 	Golden Helix
DSF
	Delusion Digital Sound File 	Delusion
DSK
	Desktop configuration 	BP - DN - BC++ - TP
DSK
	Disk Drivers 	Novell NetWare
DSK
	Logical disk file 	RT-11
DSM
	Digital Sound Module 	DSI
DSN
	Design 	Object System Designer
DSP
	Display parameters 	Signature
DSP
	Dynamic Studio Professional Module 	Dynamic Studio
DSP
	Graphics display driver 	Dr. Halo
DSP
	Norton viewer DLL 	Win
DSR
	Driver Resource 	WordPerfect for Win
DSS
	Screensaver file 	DCC
DSS
	Digital Speech Standard (Sound) 	Digital Soup
DSS
	SQL Script for .Time Framework 	Exaktime
DST
	WAIN (Scanner spec) data source DLL 	Win
DSW
	Borland C++ 4.x desktop layout file 	BCW.EXE
DSY
	DAISY container file 	ADAKTA.EXE
DT1
	Tile file 	Diablo II
DT_
	Data fork of a Macintosh file 	Mac-ette
DTA
	Data file 	Turbo Pascal - PC-File - Stata
DTB
	Database Backup for .Time Framework 	Exaktime
DTF
	Database file 	PFS - Q&A
DTL
	Django template language 	djangoproject
DTM
	DigiTrekker music module 	AWAVE
DTO
	data 	Directory Toolkit output
DTP
	Desk Top Publishing Document 	Timeworks / greenstreet Publisher3/ Greenstreet Publisher 4.5
DTP
	Page Magic 2.0 publication 	Page Magic 2.0 upgrades to Greenstreet Publisher
DTP
	Publication 	Publish-It! upgrades to Greenstreet Publisher
DVC
	Data 	Lotus 1-2-3
DVDPROJ
	iDVD project file 	iDVD (Apple iLife '08)
DVI
	DeVice Independent document 	TeX
DVP
	DESQView run-file 	DESQView
DVP
	Device parameter file 	AutoCAD
DW2
	Drawing 	DesignCAD for windows
DWB
	Coryphaeus Software Designers Workbench 	CSD
DWC
	Archive 	DWC
DWD
	DiamondWare Digitized file 	AWAVE
DWG
	Drawing 	AutoCAD, IntelliCAD, PowerCAD, Drafix, etc.
DX
	Text file 	DEC WPS/DX format - DEC WPS Plus
DXF
	Dialogue Exchange Format 	Exstream Dialogue
DXF
	Drawing Interchange File Format vector graphics 	AutoCAD, IntelliCAD, PowerCAD, etc.
DXN
	Fax 	Fujitsu dexNET
DYN
	Data 	Lotus 1-2-3
[edit] E
Ext. 	Description 	Used by
E2D
	2-dimensional vector graphics file 	Editor included in JFire
EAS
	Extended file attributes 	OS/2
EAR
	Enterprise archive 	archive
EBA
	Source code 	Emergence BASIC
EBJ
	Error-checking object file 	Geoworks
EBQ
	CITE standard electronic BQ exchange file
EC
	Error checking preprosessed Goc source code 	Geoworks
EC
	Source code 	Ecere SDK
ECC
	Error-checking file 	dvdisaster
ECMS
	Status document 	ECMerge
ECMT
	Template document / Session 	ECMerge
ED5
	EDMICS 	GCGW
EDA
	Ensoniq ASR disk image 	AWAVE
EDE
	Ensoniq EPS disk image 	AWAVE
EDF
	European data format 	Medical timeseries storage files
EDF
	Macrocom Online Kitchen-planer
EDK
	Ensoniq KT disk image 	AWAVE
EDL
	EDL 	Premiere
EDQ
	Ensoniq sq1,2/ks32 disk image 	AWAVE
EDS
	Ensoniq SQ80 disk image 	AWAVE
EDT
	Default settings 	VAX Edt editor
EDT
	Ensoniq TS disk image 	AWAVE
EDT
	External editors definitions 	DN
EDV
	Ensoniq VFX-SD disk image 	AWAVE
EEB
	Button bar for Equation Editor 	WordPerfect for Win
EFA
	Ensoniq ASR file 	AWAVE
EFA
	Encrypted File Archive 	
EFE
	Ensoniq EPS file 	AWAVE
EFE
	Ensoniq EPS instrument file 	AWAVE
EFK
	Ensoniq KT file 	AWAVE
EFQ
	Ensoniq SQ1/SQ2/KS32 file 	AWAVE
EFS
	Ensoniq SQ80 file 	AWAVE
EFT
	Ensoniq TS file 	AWAVE
EFT
	High resolution screen font 	ChiWriter
EFV
	Ensoniq VFX-SD file 	AWAVE
EFX
	Fax 	Everex EFax
EGA
	EGA display font 	Ventura Publisher
EKA
	Internal data files 	Borland's Eureka
EL
	ELISP source code file 	Emacs lisp
ELB
	Synergy/DE library
ELC
	Compiled ELISP code 	Emacs lisp
ELI
	Archive 	ELI
ELT
	Event list text file 	Prosa
EMD
	ABT Extended MoDule 	AWAVE
EMF
	Microsoft Enhanced Metafile 	
EML
	Stationery Template 	Outlook Express
EMU
	Terminal emulation data 	BITCOM
ENC
	Encoded file - UUENCODEd file 	Lotus 1-2-3 - uuexe515.exe
ENC
	Music 	Encore
END
	Arrow-head definition file 	CorelDRAW
ENFF
	Extended Neutral File Format 	
ENG
	Dictionary engine 	Sprint
ENG
	English documentation 	
ENG
	Graphics file (charting) 	EnerGraphics
ENV
	Envelope or Environments 	
ENV
	Enveloper macro 	WOPR
ENV
	Environment file 	WordPerfect for Win
EPD
	Publication 	Express Publisher
EPI
	Document 	Express Publisher
EPI
	Encapsulated PostScript graphic file 	
EPS
	Encapsulated PostScript (Graphics format) 	CorelDraw - PhotoStyler - PMView - Adobe Illustrator - Ventua Publisher
EQN
	Equation filE 	WordPerfect for Win
ERD
	Entity Relationship Diagram graphic file 	Prosa
ERL
	Erlang source code file
ERM
	Entity Relationship Diagram model file 	Prosa
ERR
	Compiler/linker error report 	
ESH
	Extended Shell batch file 	
ETH
	Document 	Ethnograph 3
ETF
	Encrypted Text File. Used in some security programs.
ETW
	Proprietary format from EnterTech for the MagicSing/Mic Karaoke product line. 	Enter-Tech
ETX
	Structure-enhanced text for some ascii text browsers 	
EUI
	Ensoniq EPS family CD image 	AWAVE
EVT
	Events descriptions 	
EVY
	Document 	WordPerfect Envoy
EWD
	Document 	Express Publisher for Windows
EX3
	Device driveR 	Harvard Graphics 3.0
EXC
	Exclude file for Optimize (do not process) (QEMM) 	QEMM
EXC
	REXX source code file 	VM/CMS
EXE
	Directly executable program 	DOS
EXF
	Excute file 	OnHand PC
EXM
	MSDOS executable, system-manager compliant (HP calculator) 	HP calculator
EXP
	Protected mode EXE by PharLap Software 	PharLap
EXP
	Exports Library File 	VisualStudio
EXT
	Extensions descriptions file 	
EXX
	Intermediate file by MsgPut 	IBM LinkWay
EZF
	Fax 	Calculus EZ-Fax
[edit] F
Ext. 	Description 	Used by
F
	Archive 	FREEZE
F
	Fortran language source code file (in fixed form) 	Many Fortran compilers
F01
	Fax 	perfectfax
F03
	Fortran language source code file (in free form) 	Many Fortran compilers
F2R
	Farandole Linear Module 	Farandole
F3R
	Farandole Blocked Linear Module 	Farandole
F4
	Fortran IV source code file 	
F4A
	Audio for Adobe Flash Player 	
F4B
	Audio Book for Adobe Flash Player 	
F4P
	Protected Video for Adobe Flash Player 	
F4V
	Video for Adobe Flash Player 	
F77
	Fortran language source code file (in fixed form) 	Many Fortran compilers
F90
	Fortran language source code file (in free form) 	Many Fortran compilers
F95
	Fortran language source code file (in free form) 	Many Fortran compilers
F96
	Fax 	Frecom FAX96
FAC
	see FACE 	
FACE
	Usenix FACE graphics file 	
FAM
	Famtasia Famicom image format 	Famtasia
FAQ
	Frequently Asked Questions text file 	
FAR
	Music format (Farandole Composer Module) 	Farandole
FAS
	Macsyma compiled program 	
FAX
	Fax (raster graphics in CCITT format) 	most Fax programs
FBM
	Fuzzy Bitmap 	
FC
	Spell checking dictionary 	Harvard Graphics 2.0
FCM
	Binary file patch file (forward compression) 	jlpak10.zip
FD
	Declaration file 	Microsoft Fortran
FD
	Field offsets for compiler 	DataFlex
FD
	Front Door' resource files 	FD
FDB
	Font Definition Block 	Ming library
FDS
	fwNES Famicom Disk System image 	fwNES
FDS
	Headerless Famicom Disk System image 	
FDW
	Form 	F3 Design and Mapping
FE
	Data 	Surface Evolver 3D surface
FEB
	Button bar for Figure Editor 	WordPerfect for Win
FEI
	Fatal Error Infotable 	Geoworks
FES
	File produced when a fileless occurrence in 3D Topicscape is exported to Windows 	3D Topicscape
FF
	Intelligont FIAS format 	
FF
	Outline font description 	Agfa Compugraphics
FFE
	Front Fareast Famicom image format 	
FFF
	Fax 	defFax
FFI
	Atech FastFont (AllType) 	
FFIVW
	File Format for the Interchange of Virtual Worlds 	
FFT
	Dca/FFT Final Form Text text file (DisplayWrite) 	
FFT
	DCA/FFT Final Form Text text file 	DisplayWrite
FH3
	Vector graphics 	Aldus FreeHand 3.x
FH4
	Vector graphics 	Aldus FreeHand 3.x
FI
	Interface file 	Microsoft Fortran
FIF
	Fractal Image Format file 	
FIG
	Figure File 	MATLAB
FIL
	Table Data 	Audit Command Language (ACL)
FIL
	File template 	Application Generator
FIL
	Filelist 	
FIL
	Files list object file 	dBASE Application Generator
FIL
	Mirror. FIL is the name given to the saved FAT by the mirror program included in some versions of DOS and in PCTools 	MS-DOS -
FIL
	Overlay 	WordPerfect
FIL
	File which was moved to the Virus Vault by AVG 	
FILM
	Filmkey film file 	Filmkey Player
FIN
	Print-formatted text file 	Perfect Writer - Scribble - MINCE
FIO
	Aldus PhotoStyler graphics filter 	
FIO
	Image PALS viewer DLL 	
FIT
	File Index Table 	WindowsNT
FIT
	see FITS 	
FITS
	Flexible Image Transport System 	
FIX
	Patch file 	
FKY
	Macro file 	FoxPro
FLA
	Adobe Flash files' basic format
FLAC
	Audio codec, Audio file format 	
FLAME
	Fractal configuration file 	Apophysis
FLB
	Format library 	Papyrus
FLC
	Animation format FLIC >320x200 	AAPlay - Autodesk AniPro
FLD
	Folder 	Charisma
FLI
	Animation format FLIC 320x200 	Autodesk Animator
FLI
	TeX font library 	EmTeX
FLM
	Film Roll 	AutoCAD/AutoShade
FLP
	Flstudio project file 	Fruity Loops (FlStudio)
FLT
	Data/file conversion filter (or overlay) 	Alsud, Microsoft Word
FLT
	Filter file 	Micrografx Picture Publisher
FLT
	MultiGen Flight 	
FLT
	Support file - graphics filter 	Asymetrix ToolBook
FLX
	Animation format 	
FLX
	Compiled binary 	DataFlex
FLV
	Flash video file 	Flash Video Player
FM
	Database 	FileMaker Pro
FM1
	Spreadsheet format overlay 	Lotus 1-2-3 release 2.x
FM3
	Device driver 	Harvard Graphics 3.0
FM3
	Spreadsheet 	Lotus 1-2-3 release 3.x
FMB
	File Manager Button bar 	WordPerfect for Win
FMF
	Font or icon file 	IBM LinkWay
FMK
	Makefile 	Fortran PowerStation
FMO
	Compiled format file 	dBASE IV
FMT
	Format file 	dBASE IV - FoxPro - Clipper 5 - dBFast
FMT
	Gate3 format file 	
FMT
	Style sheet 	Sprint
FMV
	Full Motion Video file 	
FN3
	Font file 	Harvard Graphics 3.0
FND
	Files searching properties 	Win95
FNI
	FileNet Native Document 	FileNet
FNK
	FunkTracker music module 	AWAVE, FunkTracker
FNM
	Fannie Mae Residential Loan Data (RLD) format for mortgage submission to DO/DU. 	Desktop Originator
Fnn
	DOS screen text font - height nn pixels 	fntcol13.zip
FNT
	Font file 	many
FNX
	Inactive font 	Exact
FO1
	Font file 	Borland Turbo C
FO2
	Font file 	Borland Turbo C
FOG
	Fontographer Database File 	Fontographer3.5
FOL
	Folder of saved messages 	1st Reader
FON
	Log of all calls 	Procomm Plus
FON
	Terminate phonebook 	Terminate - Terminator - Telix
FON
	Windows bitmapped font file 	Win
FONT
	Font data 	unix
FOP
	Freedom of the Press graphic file 	
FOR
	Form 	WindowBase
FOR
	Fortran language source file 	many
FOT
	Installed Truetype font 	Windows Font Installer
FOX
	Foxbase executable (precompiled .prg) 	FoxBase
FP
	Final Page file 	FoxPro for DOS
FP
	Tiff file 	TIFF/IT P1
FP
	Video file 	DVICO/TVIX MPEG1 video file
FP3
	Database 	FileMaker Pro
FP4
	Database 	FileMaker Pro
FP5
	Database 	FileMaker Pro
FP7
	Database 	FileMaker Pro
FPC
	Catalog 	FoxPro
FPD
	TMT Pascal compiled unit 	TMT Pascal
FPM
	Configuration file 	FoxPro for MacIntosh
FPT
	Foxpro memo field tables 	FoxPro
FPU
	Configuration file 	FoxPro for Unix
FPW
	Floorplan drawing 	FloorPLAN plus for Windows
FPW
	Configuration file 	Visual FoxPro
FR?
	Packed mail 	FTN software
FR3
	Renamed dBASE III+ form file 	dBASE IV
FRF
	FontMonger Database file 	FontMonger
FRG
	Uncompiled report file 	dBASE IV
FRL
	GP-Forth library 	GP-Forth
FRM
	Registration or other form 	
FRM
	Report file 	dBASE IV - Clipper 5 - dBFast
FRM
	Visual Basic Form 	Visual Basic
FRO
	Compiled report file 	dBASE IV
FRP
	Form 	PerForm PRO Plus - FormFlow
FRS
	Screen Font Resource 	WordPerfect for Win
FRT
	Additional (FPT) report description file 	FoxPro
FRT
	GP-Forth source file 	GP-Forth
FRX
	Main (DBF) report description file 	Visual FoxPro
FRX
	Visual Basic binary program file 	Visual Basic
FSA
	Applied Biosystems Genetic Analysis data file 	GeneScan
FSIM
	Simulation File Format 	Loudsoft
FSL
	Form 	Paradox for Windows
FSM
	Farandole Composer WaveSample 	Farandole
FSPROJ
	Habanero Firestarter project 	Habanero Firestarter
FST
	Linkable program 	dBFast
FSX
	Data 	Lotus 1-2-3
FTM
	Fielded Text Meta - Contains schema/Meta for a Fielded Text file 	Fielded Text
FTM
	Font file 	Micrografx
FTX
	Declared Fielded Text 	Fielded Text
FTXT
	text 	Cloanto text document
FTP
	Configuration 	FTP Software PC/TCP
FW
	Database 	FrameWork
FW2
	Database 	Framework II
FW3
	Database 	Framework III
FWEB
	Fortran WEB 	
FX
	On-line guide 	FastLynx
FXD
	Phonebook 	FAXit
FXP
	Foxpro executable (precompiled .prg) 	Visual FoxPro
FXS
	FAX Transmit Format graphics file 	WinFax
FYF
	FileLoc 	FyTek, Inc.
[edit] G
Ext. 	Description 	Used by
G
	Data chart 	APPLAUSE
G16
	GoldED for DOS compiled config 	GOLDED.EXE
G3P
	data 	Grand Prix 3 car physics
G8
	Raw graphics file (one byte per pixel) plane three 	PicLab - Cubicomb Picturemaker
GAM
	Fax 	GammaFax
GB
	Game Boy ROM 	
GB1
	Game Maker backup file (can also be GB2, GB3, etc.) 	
GBA
	Game Boy Advance ROM 	
GBC
	Game Boy Color ROM 	
GBL
	Global definitions 	VAXTPU editor
GBL
	Global module in Basic programs 	
GBR
	GIMP brush
GC1
	Lisp source code 	Golden Common Lisp 1.1
GC3
	Lisp source code 	Golden Common Lisp 1.3
GCA
	IBM GOCA 	GCGW
GCD
	Graphics 	
GCD
	General content descriptor 	Wireless devices
GCF
	Game cache file 	Steam content delivery system
GCX
	Graph file 	Mac OS X Grapher
GD3
	Game Doctor Super NES ROM image
GDF
	General Data Format for Biomedical Signals 	Biomedical signal processing, Brain Computer Interfaces
GDF
	Dictionary file 	GEOS
GDF
	Geographical Data Format 	Various mapping software
GDF
	IBM Graphics Data Format 	Legacy IBM systems
GDL
	Data 	ArchiCAD model
GDS
	McDonnell-Douglas Things 	
GE
	GEcho config file 	GEcho
GED
	GEDCOM 	Genealogy data exchange
GED
	EDITOR's native file format 	Arts & Letters
GED
	GoldED for DOS compiled config file 	GOLDED.EXE
GED
	Graphics editor file 	EnerGraphics
GED
	Game Editor Data / project file 	Game Editor
GEM
	Vector graphics file 	GEM - Ventura Publisher
GEN
	Compiled template 	dBASE Application Generator
GEN
	Generated text 	Ventura Publisher
GEO
	Geode 	Geoworks
GEO
	GEOS specific file (application) 	GEOS
GEO
	GoldED for OS/2 compiled config file 	GED2.EXE
GEX
	GEcho config file 	GEcho
GFB
	Compressed GIF image created by GIFBLAST 	gifblast.exe
GFO
	SGI Radiosity 	
GFT
	Font 	NeoPaint
GFT
	GEM-translator font file 	
GFX
	Instant Artist graphics Files 	Instant Artist
GFX
	PCBoard @X-coded colorful text 	GFX2COM - GFX2EXE
GHO
	Norton Ghost File (first file) 	Symantec
GHS
	Norton Ghost File (split file) 	Symantec
GIB
	Chart 	Graph-in-the-Box
GIB
	GIMP animated brush
GID
	Help index 	windows 95 help
GIF
	Compuserves' Graphics Interchange Format (bitmapped graphics) 	QPeg - Display - CompuShow
GIW
	Presentation 	Graph-in-the-Box for Windows
GKH
	Ensoniq Disk Image (VFX, SD, EPS, ASR, TS) 	Ensoniq
GKS
	Graphics Kernel System 	
GL
	Animation format 	grasprt.exe, PV
GL
	Animation 	GRASP GRAphical System for Presentation
GLB
	Global module in Basic programs 	
GLM
	Datafile 	Glim
GLO
	Global module in Basic programs 	
GLS
	Datafile 	Across
GLY
	Winword Glossary 	Microsoft Word
GM6
	Game Maker Editable file as of version 6.x
GMD
	Game Maker Editable file up to version 5.x
GMF
	CGM graphics file 	APPLAUSE
GMK
	Game Maker Editable file as of version 7.x
GML
	Game Maker GML file
GMOD
	Data 	Golgotha 3D model
GMP
	Geomorph tile map 	SPX
GMS
	Ghost Mouse Script
GMS
	Gesture and Motion File Formats
GMT
	data 	RFactor car physics
GOC
	Goc source code file 	Geoworks
GOE
	GOES graphic file 	
GOH
	Goc header file 	Geoworks
GP5
	Guitar Pro 5 song 	Guitar Pro 5
GP
	Geode parameter file 	Geoworks Glue
GP4
	data 	Grand Prix 4 car physics
GPH
	Graph 	Lotus 1-2-3/G
GPK
	Omnigo program package 	
GPX
	GPS eXchange Format 	
GR2
	Screen driver 	Windows 3.x
GRA
	Datafile 	SigmaPlot
GrADS
	Metafile 	
GRAFFLE
	OmniGraffle graph file 	
GRASP
	Graphical System for Presentation 	
GRB
	T-FLEX CAD file 	Top Systems
GRB
	MS-DOS Shell Monitor file 	MS-DOS 5
GRD
	Drivers for GRX (graphics library) 	GRX (c) Free Soft. Found.
GRDNT
	Image format used in the core of some very obscure customized operating systems to represent gradients; see also SCTOR 	
GRE
	data 	Grenoble Thermal Ellipsoids Plot Program
GRF
	Graph file 	Graph Plus - Charisma
GRIB
	Gridded Binary 	
GRN
	Drivers for GRX (graphics library) 	GRX (c) Free Soft. Found.
GRP
	Group file 	Windows 3.x - Papyrus
GRP
	Pictures group 	PixBase
GRY
	Graphics format (RAW GREYz) 	
GS1
	Presentation 	GraphShow
GS3
	data 	GameStarter
GSA
	data 	Microsoft Office Groove Space Archive
GSD
	Vector graphics 	Professional Draw
GSM
	Raw GSM 6.10 audio stream 	AWAVE
GSW
	Worksheet 	GraphShow
GTA
	data 	Microsoft Office Groove Tool Archive
GUP
		PopMail
GV
	GrandView outline file 	
GVO
	Data 	GFXFX Vector Object
GWI
	Groupwise File 	Local saved Email
GXL
	Graphics library 	Genus
GZ
	Archive 	GNU zip - WinZipNT
GZR
	data 	GunZ action replay
[edit] H
Ext. 	Description 	Used by
H!
	On-line help file 	Flambeaux Help! Display Engine
H!
	Pertext database 	HELP.EXE
H--
	C\u2014language header 	Sphinx C--
H
	Header file (usually C language) 	Watcom C/C++
H++
	Header file 	C++
HA
	Archive 	HA
HAL
	Data file 	Hyper Access Lite OS/2
HAM
	Disk Drivers NPA 	Novell NetWare
HAM
	Hold And Modify 	Deluxe Paint image file
HAP
	Archive 	HAP3
HBC
	Compressed Archive File (Shrink Algorithm) 	Hyperbac
HBC
	Compressed Archive File (Shrink Fast Algorithm) 	Hyperbac
HBE
	Compressed, Encrypted Archive File (Shrink & AES256-bit Encryption) 	Hyperbac
HBK
	MathCAD handbook 	MathCAD
HC
	Header file 	
HCG
	Document 	HCLab
HCGS
	Document 	HCLab
HDD
	data 	disk image
HDD
	HotDisc Designer label
HDF
	Amiga Hard Disk Image
HDF
	Help file 	Help Development Kit
HDF
	Hierarchical Data File graphics file 	SDSC Image Tools
HDL
	Alternate download file listing 	Procomm Plus
HDR
	Datafile 	Egret
HDR
	Message header text 	Procomm Plus - 1st Reader
HDR
	PC-File+ Database header 	
HDR
	SPOT image file 	
HDS
	Hierarchical Data System 	
HDW
	Vector graphics 	Harvard Draw
HDX
	Help index 	AutoCAD - Zortech C++
HDZ
	Amiga Zip compressed Hard Disk Image
HEP
	Novell Help Librarian Data File 	Novell NetWare
HEX
	Hex dump 	
HFI
	HP Font Info file 	GEM
HGL
	Highlight groups definitions 	DN
HGL
	HP Graphics Language graphics file 	
HH
	C++ header file 	
HHH
	Precompiled header file 	Power C
HHP
	Help information for remote users 	Procomm Plus
HI
	Game high scores table 	
HIN
	Molecule 	HyperChem
HIS
	History of executing/viewing/editing 	DN
HIS
	Yard Information File 	FYM
HKM
	Stores sound in a bitmapped graphics file 	
HLB
	Help library 	VAX
HLP
	Help file 	WinHelp, Help Explorer Viewer
HLX
	Multi Edit help file 	MultiEdit 5.0
HLZ
	Multi Edit packed help file 	MultiEdit
HMI
	Music format (MIDI) 	
HMM
	Alternate Mail Read option menu 	Procomm Plus
HMP
	Music format (MIDI) 	
HMP
	Hump Setup File - Obsolete as of version 2.4 (See SET and SWT files) 	FYM
HNC
	CNC program files Heidenhain (?) dialog 	
HOF
	Hall Of Fame (game scores) 	
HP
	Printout file for HP printers/plotters (HP/GL) 	
HP8
	ASCII text HP Roman8 character set 	NewWave Write
HPF
	HP LaserJet fonts 	PageMaker
HPG
	see HPGL 	
HPGL
	Plotter file vector graphics (Hewlett-Packard Graphics Language) 	AutoCad - Harvard Graphics
HPI
	Font information file 	GEM
HPJ
	Help project 	Microsoft Help Compiler for Windows - HC.EXE
HPK
	Archive 	HPACK
HPM
	Alternate Main menu for privileged users 	Procomm Plus
HPM
	EMM text 	HP NewWave
HPM
	High Performance Map 	Quaestor 1.x
HPP
	C++ header file 	Zortech C++ - Watcom C/C++
HPPCL
	Hewlett-Packard Printer Control Language 	
HQX
	Archive (ASCII Mac) 	BINHEX
HRF
	Graphics file (Hitachi Raster Format) 	
HRM
	Alternate Main menu for limited/normal users 	Procomm Plus
HRZ
	Graphics format 	SSTV
HS2
	Monochrome image 	Postering
HSC
	2-op FM music 	HSC tracker - hscplay.exe
HSH
	Disk image hash file 	DriveSnapshot
HSI
	Handmade Software Inc. graphics file almost JPEG 	Image Alchemy
HST
	History file 	Procomm Plus
HTM
	see HTML 	
HTML
	Hypertext Markup Language (WWW) 	Netscape - Mosaic - many
HTX
	Hypertext file 	
HWD
	Presentation 	Hollywood
HWP
	Hangul Word Processor Document 	Hangul (word processor)
HXM
	Alternate Protocol Selection menu for all users 	Procomm Plus
HXS
	Microsoft Help 2 compiled help file 	Microsoft Windows, Help Explorer Viewer
HXX
	C++ header file 	
HY1
	Hyphenation algorithms 	Ventura Publisher
HY2
	Hyphenation algorithms 	Ventura Publisher
HYC
	Data 	WordPerfect
HYD
	Hyphenation dictionary 	WordPerfect for Win
HYP
	Archive 	HYPER
[edit] I
Ext. 	Description 	Used by
I
	Preprocessor output file 	Borland C Preprocessor
IAK
	Internet Access Kit 	OS/2
IAM
	Assembly file 	Autodesk Inventor
IAX
	Bitmap graphics (IBM Image Access eXecutive) 	
IAX
	data 	InstallAnywhere.NET project
IBG
	PDS graphic file 	
IBM
	Archive (Internal IBM only) 	ARCHDOS
ICA
	Bitmap graphics (Image Object Content Architecture) 	
ICB
	Bitmap graphics 	
ICC
	ICC configuration 	
ICE
	Archive 	Cracked LHA (old LHA)
ICM
	ICC configuration 	
ICN
	ICON source code file 	
ICO
	Icon file 	ICONEDIT.EXE; Microsoft Windows
ID
	Disk identification file 	
IDB
	IDA database 	IDA
IDB
	VC++ Minimum Rebuild Dependency File 	Visual C++
IDC
	IDA C language source 	IDA
IDE
	Borland C++ 4.x IDE project 	BCW.EXE
IDF
	MIDI instrument description 	
IDS
	IDA imported names format 	IDA
IDW
	Vector graphics 	IntelliDraw
IDW
	Drawing file 	Autodesk Inventor
IDX
	Index 	many - FoxPro; also unrelated Quicken file format.
IFD
	Form 	JetForm Design
IFF
	Interchange Format File (IFF) 	EA Software - Convert (C) Villena - Amiga
IFF
	Sun TAAC Image File Format 	SDSC Image Tool
IFP
	Script 	KnowledgeMan
IFS
	Fractal image compressed file 	Yuvpak
IFS
	Installable file system 	OS/2
IGES
	Initial Graphics Exchange Specification 	
IGF
	Inset Systems 	GCGW
IGC
	Flight tracks downloaded from GPS devices in the International Gliding Commission's prescribed format
IHP
	Watcom help file 	whelp.exe
IHS
	Inbound History 	Bink/+
IIW
	Power Point Image Importer Wizard
IL
	hDC Designer Icon Lin dll format 	
ILB
	Data 	Scream Tracker
ILG
	data 	LaTeX Index Generation log
ILK
	Outline of program's format 	Microsoft ILink incremental linker
IM
	Auran Jet indexed mesh file 	Trainz
IM8
	Sun raster graphics file 	
IMA
	Mirage vector graphics 	EGO - Chart - Autumn
IMG
	ADEX graphic file 	
IMG
	Disk Image 	NC 5.0
IMG
	GEM bitmapped graphics file 	Ventura
IMG
	Image for Windows/Image for DOS Disk image 	TeraByte, Inc. dba TeraByte Unlimited
IMG
	Vivid IMG file 	
IMI
	image 	Magellan Meridian map
IMI
	image 	Magellan eXplorist map
IMP
	Spreadsheet 	Lotus Improv
IMQ
	Image presentation 	ImageQ
IN$
	Installation file 	HP NewWave
IN3
	Input device driver 	Harvard Graphics 3.0
INB
	Test script 	Vermont HighTest
INC
	Include file 	several programming languages
IND
	Data Index 	dBASE IV
INDD
	InDesign Document 	Adobe InDesign
INF
	Information text file (ASCII) 	
INF
	Install script 	
INF
	OS/2 hypertext help system file 	VIEW.EXE
INF
	Type 1 LaserJet font information file 	soft font installers
INFO
	GNU info reader (output from texinfo) 	unix
INFO
	Icon Data (Amiga) 	
INGR
	Intergraph Raster File Format 	
INI
	Initialization file 	
INK
	Pantone reference fills file 	CorelDRAW
INS
	Data 	WordPerfect
INS
	Ensoniq Instrument File 	Ensoniq
INS
	Installation script 	1st Reader
INS
	Instrument music file (Adlib) 	
INT
	Borland Interface Units 	
INT
	Program saved in Internal (semi-compiled) format 	Signature
INT
	Source of Borland interface module 	
INX
	Index 	Foxbase
IO
	Archive 	CPIO
IOB
	3d graphics database in TDDD format 	
IOC
	Organizational chart 	Instant ORGcharting!
ION
	4DOS descript.ion file (file descriptions) 	4DOS
IP
	Immortal Player file 	Immortal Player
IPC
	Intellitec Program Configuration - used to configure vehicle electronics 	Intellitec
IPF
	Interchangeable Preservation Format 	SoftPres
IPG
	iPod game file 	iTunes and iPod
IPH
	Hi-Res Image 	InterPaint
IPL
	Pantone Spot reference palette file 	CorelDRAW
IPN
	Intecplan project 	Intecplan Business Plan Software
IPS
	IPS Patching Format (International Patching System) 	Rom hacking community
IPT
	Part file 	Autodesk Inventor
IPT
	MultiColor Image 	InterPaint
IRS
	Resource (WordPerfect) standard.irs 	WordPerfect
IRT
	Data 	IRIT 3D model
IRTR
	Graphicon-2000 Interactive Real-Time PHIGS 	
ISD
	Spelling Checker dictionary 	RapidFile
ISH
	Archive 	ISH
ISMA
	Output Video file 	Islam Abusa'a Software
ISO
	ISO-9660 table 	see: List of ISO image software
IST
	Digitrakker Instrument File 	AWAVE
IT
	Impulse Tracker music file 	Impulse Tracker
IT
	Settings 	intalk
ITF
	Interface file 	JPI TopSpeed Pascal
ITL
	iTunes music library
ITN
	Itinerary file 	TomTom PNDs
ITT
	IconTweaker Theme 	
IV
	SGI Inventor 	
IV-VRML
	Inventor VRML Format 	
IVE
	OpenSceneGraph 3D model
IVI
	Image file 	ImmerVision
IVL
	Lensflare file 	ImmerVision
IVP
	Panorama file 	ImmerVision
IVU
	User Interface file 	ImmerVision
IW
	Presentation flowchart 	IconAuthor - HSC InterActive
IWA
	Text file 	IBM Writing Assistant
IWD
	Call of Duty Map - Game Data Archive 	Activision, Inc.
IWP
	Text file 	Wang
IX
	data 	dtSearch index
IZT
	Izl binary token file 	IZL
[edit] J
Ext. 	Description 	Used by
J2C
	JPEG 2000 image 	
JAM
	Jam messagebase 	FTN software
JAM
	Jam music score 	Jam
JAR
	Archive 	JAR. Java Games and Applications
JAS
	see JASC 	
JASC
	Graphics format (JASC) 	
JAV
	see JAVA 	
JAVA
	Java source code file 	
JBD
	Datafile 	SigmaScan
JBIG
	Joint Bilevel Image Group 	
JBX
	Project file 	Project Scheduler 4
JCN
	JobClock.Net Synch File
JET
	Fax 	Hybrid JetFax
JFF
	see JFIF 	
JFIF
	JPEG File Interchange Format 	
JIF
	see JFIF 	
JMS
	Music format (JMusic file) 	UltraForce
JOB
	Gravostyle engraving pattern file 	Gravostyle/Gravograph
JOB
	QUEUE output file 	RT-11
JOR
	Journal file SQL 	
JOU
	Journal backup 	VAX Edt editor
JP2
	JPEG 2000 image 	
JPC
	Graphics 	Japan PIC
JPEG
	Joint Photography Experts Group graphics file format 	QPeg - FullView - Display
JPG
	see JPEG 	
JRE
	Java Runtime Environment 	Java
JRN
	JMP journal 	JMP
JSP
	Java Server Pages 	
JS
	JScript script file 	Javascript
JTF
	Fax 	Hayes JT Fax
JTF
	Graphics (TIFF file with JPEG compression) 	
JK
	Root File of a lol 	Earl Grey
JVX
	Data 	JavaView object
JW
	Text document 	JustWrite
JWL
	Library 	JustWrite
JZZ
	Spreadsheet 	Jazz
[edit] K
Ext. 	Description 	Used by
K2A
	Data 	Prince of Persia 3D object
K3D
	Description of macro language 3DS 	3DS
KAP
	Map Info Sea Chart 	
KAR
	Music format (Karaoke) 	
KAR
	Precompiled .prg for KARAT 	Rus. FOX+ 2.0
KB
	Keyboard script 	Borland C++ 4.5
KB
	Program source 	Knowledge Pro
KBASIC
	Source 	KBasic
KBD
	Keyboard mapping 	LocoScript - Signature - Procomm Plus
KBM
	Keyboard mapping 	Reflection 4.0
KCL
	Lisp source code 	Kyoto Common Lisp
KDB
	KeePass 1.x database file 	KeePass
KDBX
	KeePass 2.x database file 	KeePass
KDC
	Kodak Digital Camera (graphics) 	PhotoEnhancer by PictureWorks
KEP
	(unknown) 	(unknown)
KEX
	Kedit Macro File 	Kedit
KEY
	Datafile 	Forecast Pro
KEY
	Keynote presentation file 	Keynote (Apple iWork '08)
KEY
	Keyboard macros 	
KEY
	OS/2 archive .key-file (i.e. OS2.KEY) 	OS/2
KEY
	Security file e.g. Shareware Registration info 	
KFX
	Kofax Group 	GCGW
KIT
	Power Chords drum kit file 	Power Chord
KMC
	KatzReview's MegaCrammer
KML
	Kedit Macro Library / Keyhole Markup Language 	Google Earth
KMY
	data 	KMyMoney
KMZ
	Keyhole Markup Language (Zip compressed) 	Google Earth
Knn
	Database key file 	Clarion
KNO
	Personal Knowbase data file 	Personal Knowbase
KPL
	source code 	Phrogram
KPP
	Toolpad 	SmartPad
KPS
	IBM KIPS bitmap graphics 	
KR1
	Kurzweil 2000 sample file 	AWAVE
KR2
	Kurzweil 2000 sample file 	AWAVE
KRZ
	Kurzweil K2000 File 	Kurzweil
KS
	Source code 	KonsolScript
KS3
	Data 	3D Forgastest Editor object
KTU
	Know The Unknown Online Service Packs 	Unknownsoft
KYB
	Keyboard mapping 	FTP Software PC/TCP
[edit] L
Ext. 	Description 	Used by
L
	LEX source code file 	
L
	Linker directive file 	WATCOM wlink
L
	LISP source code file 	
LA0
	Datafile 	SCUMM index file
LAB
	Datafile 	NCSS - SOLO
LAB
	Mailing labels 	Q+E for Microsoft Excel
LAN
	Erdas image file 	
LAN
	LAN Drivers 	Novell NetWare
LAY
	Word chart layout 	APPLAUSE
LBG
	Label generator data 	dBASE IV
LBL
	Label 	dBASE IV - Clipper 5 - dBFast
LBM
	Graphics format (Amiga) 	Pic-view - Deluxe Paint
LBM
	Linear bitmap graphics 	XLib
LBO
	Compiled label 	dBASE IV
LBR
	.LBR Archive 	forCP/M and MS-DOS using the LU program
LBR
	Display driver 	Lotus 1-2-3
LBT
	Additional (FPT) label description file 	FoxPro
LBX
	Main (DBF) label description file 	FoxPro
LCF
	Linker Control File 	Norton Guides compiler
LCH
	Chart 	IBM Works for OS/2
LCK
	Lockfile 	Paradox
LCL
	Data (FTP Software PC/TCP) 	
LCL
	Data 	FTP Software PC/TCP
LCN
	Lection 	WordPerfect
LCS
	Datafile 	ACT! History Files
LCW
	Spreadsheet 	Lucid 3-D
LD
	Long Distance codes file 	Telix
LDA
	Absolute binary file (load image) 	PDP-11, RT-11
LD1
	Overlay file 	dBASE
LDB
	Data filer database 	IBM Works for OS/2
LDB
	Overlay file 	Microsoft Access
LDF
	Data filer form 	IBM Works for OS/2
LDF
	Library definition file 	Geoworks Glue
LE
	DOS/4GW executable image 	DOS/4GW PM 32X DOS Extender
LES
	Lesson (check *.cbt) 	
LEV
	Level file 	NetHack 3.x
LEX
	Dictionary 	Microsoft Word - Lexicon
LFL
	LucasArts resource file 	
LFD
	LucasArts resource file 	LucasArts games
LFT
	Laser printer font 	ChiWriter
LG
	Logo procedure definitions 	LSRHS Logo
LGO
	Logo for header and footer 	SuperFax
LGO
	Startup logo code 	Windows 3.x
LHA
	Archive 	LHA/LHARC
LHW
	Amiga archive 	LHWARP
LIB
	Library file 	several programming languages
LIC
	License file used by some programs to put their license on disk 	
LIF
	Archive 	
LIF
	CA Clipper packed file 	CA Clipper installer
LIF
	Logical Interchange Format data file 	Hewlett-Packard
LIM
	Archive 	LIMIT
LIN
	Line types 	AutoCAD
LIS
	Listing 	VAX
LIT
	Web3D File 	Web3D
LIX
	Log file (history) 	Audit Command Language (ACL)
LJ
	Text file for HP LJ II printer 	
LL3
	LapLink III related file (document) 	LapLink III
LM
	Auran Jet LOD mesh table (text file to control LODs) 	Trainz
LMP
	Demo for Doom (computer 3d game) 	Doom - Doom2
LNG
	Language definition file 	
LNK
	Linker response file 	.RTLink
LNK
	Linker script 	
LNK
	Windows 95 shortcut 	Windows 95
LNK
	Windows XP shortcut 	Windows XP
LOD
	Load file 	
LOG
	Log file 	Numerous systems
LOM
	3D Model 	Lock On: Modern Air Combat
LPC
	Printer driver 	TEKO
LRC
	Lyrics data
LRF
	Linker response file 	Microsoft C/C++
LRF
	Unencrypted BroadBand eBook file 	Sony Librie eBook reader
LRP
	Report 	IBM Works for OS/2
LRS
	Language Resource File 	WordPerfect for Win
LRX
	Encrypted BroadBand eBook file 	Sony Librie eBook reader
LSA
	Lightscape Technologies ASCII 	
LSB
	Lightscape Technologies Binary 	
LSP
	LISP source code file 	Xlisp, AutoLISP
LSS
	Spreadsheet 	Legato - IBM Works for OS/2
LST
	Aus. BOM Hourly weather Data
LST
	Filelist 	FRQView
LST
	Keyboard macro 	1st Reader
LST
	List file (archive index - compiler listfile) 	
LST
	Listing (e.g. source code) 	
LST
	Map list 	Holux - Alan
LST
	Spool file 	Oracle
LST
	SLP output file 	RT-11
LTA
	Data 	LithTech ASCII 3D object
LTM
	Form (Lotus Forms) 	Lotus
LUA
	Lua script file 	Microsoft Visual C++, Notepad++
LWD
	Text document 	LotusWorks
LWO
	Lightwave Object Format 	
LWP
	Word processor 	IBM Works for OS/2, Lotus Wordpro
LXF
	Lego Exchange Format 	Lego Digital Designer data file
LY
	LilyPond Notation File 	LilyPond
LYR
	Lyrics (ASCII) 	
LZ
	Archive 	Lzip
LZD
	Difference file for binaries 	LDiff 1.20
LZH
	Archive 	LHA/LHARC
LZS
	Archive 	LARC
LZW
	Archive 	LHWARP
LZX
	Amiga Archive 	LZX
[edit] M
Ext. 	Description 	Used by
M
	MATLAB M-File 	MATLAB
M3U
	M3U playlist file 	WinAMP, XMMS
M3U8
	Unicode version of M3U playlist file (UTF-8) 	WinAMP, XMMS
M4A
	Advanced Audio Coding 	
M7P
	Multilizer 2007 and 2009 localization project file 	Multilizer
MAI
	Mail 	VAX
MAK
	Makefile 	
MAK
	Project file 	VB - VC ++
MAN
	User guide (manual) 	
MAP
	Color palette file 	
MAP
	Format data 	Micrografx Picture Publisher
MAP
	Linker map file 	
MAP
	Map file (usually created by compilers) 	
MAP
	Map 	Atlas MapMaker
MAP
	Network map 	AccView
MAP
	Game map for Duke Nukem 3D
MAR
	Assembly program 	VAX Macro
MAR
	Microsoft ARchive 	MSN Explorer (possibly other Microsoft products too)
MAR
	Mozilla ARchive 	Mozilla Updater (used to house binary updates to products)
MAS
	SmartMaster set 	Freelance Graphics
MAT
	Data 	MATLAB
MAX
	MAX source code file 	
MB
	Memo field values for database 	Paradox
MBK
	Multiple index file backup 	dBASE IV
MBX
	Mailbox data 	Eudora/ZERBERUS
MCC
	Configuration file 	Mathcad
MCD
	MathCad file 	MathCad
MCF
	Font file 	Mathcad
MCF
	Photo book or photo calendar layout file 	FotoInsight Designer
MCF
	Multimedia Container Format (predecessor of Matroska)
MCI
	MCI command script 	Media Control Interface
MCL
	Multi Edit macro library 	Multi Edit
MCL
	Cartesian manipulator for laser systems
MCP
	Application script 	Capsule
MCP
	Printer driver 	Mathcad
MCW
	Text file 	MacWrite II
MDL
	Quake 1 Model File 	id Software
MD2
	Quake 2 Model File 	id Software
MD3
	Quake 3 Model File 	id Software
MD5
	Doom 3 and Quake 4 Model File 	id Software
MD
	Archive 	mdcd10.arc
MDA
	Data 	Microsoft Access
MDA
	Microsoft Access system database 	Microsoft Access
MDB
	Microsoft DataBase 	Microsoft Access
MDF
	Several uses
MDL
	Model 	3D Design Plus or Simulink
MDL
	Spreadsheet 	CA-Compete!
MDM
	Modem definition file 	TELIX
MDR
	Microdrive file 	ZX Spectrum emulator by g.a.lunter
MDS
	Midi Session 	Sound Imp.
MDT
	Data table 	Microsoft ILink incremental linker
MDX
	Multiple index file 	dBASE IV
MDZ
	Text description of music module 	Cubic Player - Cross-View
ME
	MultiEdit configuration 	MultiEdit
ME
	Text file READ.ME 	
MEB
	Macro Editor bottom overflow file 	WordPerfect Library
MEC
	MECCA source 	Maximus
MED
	Macro Editor delete save 	WordPerfect Library
MED
	Music format 	MED/OctaMED
MEM
	Macro Editor macro 	WordPerfect Library
MEM
	Memory variable save file 	dBASE IV - FoxPro - Clipper
MEM
	Memos datafile 	Clarion
MEQ
	Macro Editor print queue file 	WordPerfect Library
MER
	Macro Editor resident area (vakioalue) 	WordPerfect Library
MES
	Macro Editor work space file 	WordPerfect Library
MES
	Message 	
MET
	Document 	Omnipage Pro
MET
	Macro Editor top overflow file 	WordPerfect Library
MET
	OS/2 graphics metafile 	PICVIEW.EXE
MEU
	Menu group 	DOS Shell
MEX
	Macro Editor expound file 	WordPerfect Library
MEX
	MEX file (executable command) 	Matlab
MF
	Metafont file 	TeX
MFA
	Source code file 	Multimedia Fusion 2 / The Games Factory 2
MFF
	MIDI 	Cakewalk, MTPro 4
MFM
	Music format 	DMP
MGF
	Font 	Micrografx
MGF
	Materials and Geometry Format 	
MGX
	Designer 4.1 Drawing 	Designer 4.1
MHT
	Web Archive Single File
MIB
	Snmp MIB file 	
MID
	Standard MIDI file 	music synthetizers
MIDI
	See MID
MIFF
	Magick Image File Format 	
MII
	Datafile 	MicroStat-II
MIME
	Message in MIME format (RFC822) 	
MIO
	MyInfo topic 	Milenix MyInfo
MIS
	Mission, used by many games 	
MIX
	Object file 	Power C
MK
	Makefile 	
MK
	Makefile 	
MK
	Usually makefile 	
MKE
	Makefile 	Microsoft Windows SDK
MKG
	Makefile 	
MKI
	Graphics format (Japan MKI) 	
MKI
	Japanese graphics MAKIchan format 	MagView 0.5
MKS
	Data 	TACT
MKV
	Matroska Multimedia Container 	Media Player Classic, Windows Media Player, Matroska Splitter
ML3
	Project 	Milestones 3.x
MLB
	Macro library file 	RT-11, Symphony
MLI
	3DS Materials Libraries 	3D Studio
MLRAW
	Data 	Moonlight Creator RAW format 3D object
MLV
	LabVIEW MathScript
MM
	Text file 	MultiMate Advantage II
MMF
	Mail message file 	Microsoft Mail
MMM
	Multimedia movie file, RIFF RMMP format 	MacroMind Director 3.x
MMO
	Memo writer file 	RapidFile
MMP
	Output video format from Bravado board 	
MND
	Menu source 	AutoCAD Menu Compiler
MNG
	Map 	DeLorme Map'n'Go
MNT
	Additional (FPT) menu description file 	FoxPro
MNT
	Menu memo 	FoxPro
MNU
	Advanced macro file 	HP NewWave
MNU
	Menu 	AutoCAD Menu Compiler - Norton Commander - Signature
MNU
	Microsoft Mouse menu (for DOS apps) 	
MNX
	Compiled menu file 	AutoCAD
MNX
	Main (DBF) menu description file 	FoxPro
MNY
	Account book 	Microsoft Money
MO?
	Packed mail 	FTN software
MOB
	Device definition file 	PEN Windows
MOBI
	eBook 	Mobipocket
MOD
	Modula language source 	
MOD
	MODULA-2 source code file 	Clarion Modula-2
MOD
	Module\u2014used by Windows for DLL which implement DOS support 	Win
MOD
	Music format (Amiga module) 	DMP - ST - MDP - VP
MOL
	MOD4WIN PlayList 	Mod4Win
MOL
	MDL Molfile 	RasMol
MOL2
	Tripos\u2019 Sybyl MOL2 Format 	SYBYL, RasMol
MON
	SYSGEN monitor build procedure 	RT-11
MON
	Monitor description 	ReadMail
MOP
	MOPAC input file 	MOPAC, RasMol
MOV
	Animation format (Mac) 	QuickTime
MOV
	Movie file 	AutoCAD AutoFlix
MP2
	Mpeg audio file 	xing
MP3
	MPEG audio stream, layer 3 	AWAVE, CoolEdit(+PlugIn)
MP4
	multimedia container format, MPEG 4 Part 14 	
MPA
	MPEG audio stream, layer 1,2,3 	AWAVE
MPC
	Calendar file 	Microsoft Project
MPC
	Musepack audio 	
MPEG
	multimedia containter format, video, audio 	MPEG Player
MPG
	see MPEG 	
MPKG
	Multipackage installer script 	Mac OS X
MPL
	MediaRack Midi Playlist 	MediaRack
MPM
	MathPlan macro 	WordPerfect Library
MPP
	Project file 	Microsoft Project
MPQ
	Mo'PaQ Archive 	Blizzard games
MPR
	Generated executable menu file 	FoxPro
MPR
	Multilizer 5.x and 6.x localization project file 	Multilizer
MPT
	Bitmap graphics (Multipage TIFF) 	
MPV
	View file 	Microsoft Project
MPX
	Compiled executable menu file 	FoxPro
MPX
	Video format 	
MPZ
	Miradi Project Zipfile 	Miradi
MRB
	Multiple Resolution Bitmap graphics file 	Microsoft C/C++
MRK
	Windows User Benchmark 	Win95
MRS
	Macro Resource file 	WordPerfect for Win
MS
	Microsoft antivirus report 	MSAV
MSC
	Microsoft C makefile 	
MSI
	Windows Installer Package 	Windows Operating Systems
MSDL
	Manchester Scene Description Language 	
MSG
	Message base (e.g. HMB) 	
MSG
	Message text file (ASCII) 	
MSG
	ZVoice digitized voice file 	
MSE
	Set file 	Magic Set Editor
MSO
	Microsoft Word OLE Web Page Storage Stream 	Microsoft Office
MSP
	Bitmap graphics file 	Microsoft Paint
MSP
	Graphics format 	Microsoft Paint
MSPRODUCER
	Media Project 	Microsoft Producer (for Microsoft PowerPoint XP/2003) Project
MSQM
	data 	Microsoft Message Queuing
MSN
	Project 	National Instruments for NI MultiSim-Electronic Circuit simulator
MSS
	Manuscript text file 	Perfect Writer - Scribble - MINCE - Jove
MST
	Document 	MS Test
MST
	Minispecification file 	Prosa
MST
	Setup script file 	Microsoft Windows SDK
MSW
	Text file 	Microsoft Word
MSX
	CP/M archive 	MSX
MTH
	Math file 	Derive
MTL
	Wavefront 	
MTM
	Music format 	MultiTracker
MTS
	Master Track Pro Files 	MTPro 4
MTS
	data 	F1 2001, F1 2002 and F1 Challenge 1999 - 2002 car physics (All from the EA Sports F1 Series)
MTV
	MTV Ray Tracer graphic file 	
MTW
	Datafile 	Minitab
MU
	Quattro pro for DOS Menu definition file 	Quattro Pro
MUS
	Finale music document. 	Finale
MUS
	Music format (MIDI in Doom) 	
MUS
	Sound file 	MusicTime
MUZ
	Hover Game MIDI File 	Windows' Hover! Game [1]
MVF
	Stop frame file 	AutoCAD AutoFlix
MVI
	Movie command file 	AutoCAD AutoFlix
MVO
	Data 	Mad Virgin 3D object
MVW
	Log file 	Saber LAN
MWF
	Animation 	ProMotion
MWS
	MWave DSP synths instrument 	AWAVE
MXF
	Material exchange format (RFC 4539, SMPTE 377M) 	
MXL
	PackRat 5.0 support DLLs 	PackRat 5.0
MXM
	Material 	Maxwell Render
MXP
	Adobe Extension File 	Adobe Dreamweaver and Adobe Flash
MXP
	3ds Max Configuration File 	3ds Max
MXP
	MasterCook exported recipe 	
MXT
	Data 	Microsoft C
MYP
	Presentation 	MM Make Your Point
MZ
	Binary-format Map 	MazeEdit
MZE
	Text-format Map 	MazeEdit
MZG
	Binary-format Map Collection 	MazeEdit
MZX
	Binary-format Encrypted Map 	MazeEdit
[edit] N
Ext. 	Description 	Used by
NAM
	Name Space Modules 	Novell NetWare
NAP
	Naplps file (VideoShow) 	EnerGraphics
NAPLPS
	North American Presentation Layer Protocol Syntax 	
NB
	Text file 	Nota Bene
NB
	Wolfram Mathematica Notebook 	Mathematica
NBF
	Nokia Backup File 	Nokia Mobile Phones
NC
	Graphics 	netcdf
NC
	Instructions for NC (Numerical Control) machine 	CAMS
NC
	Non-error checking preprosessed Goc source code 	Geoworks
NCC
	CNC (Computer Numeric Control) control file 	CamView 3D
NCD
	Norton Change Directory support file 	Norton Commander
NCP
	Re-volt Collision file 	Re-volt
NDB
	Network database 	Intellicom - Compex
NDS
	Nintendo DS ROM file used for Homebrew and commercial (Game) files on DS 	
NDL
	Nodelist file 	
NDX
	Index file 	dBASE II - III - IV - dBFast
NEO
	Raster graphics file 	Atari Neochrome
NES
	iNES ROM image format 	
NET
	Network configuration/info file 	
NEU
	Pro/Engineer neutral file format 	PTC Pro/Engineer
netCDF
	Network Common Data Format 	
NEW
	New info 	
NFF
	Haines Neutral File Format 	
NFF
	WorldToolKit Neutral File Format 	
NFO
	Folioview database 	
NFO
	Help format 	Nextpage Folio
NFO
	Info file 	Compact NFO Viewer
NG
	Hypertext Database 	Norton Guide
NGO
	NG linker object file 	NGML
NGS
; 	NG compiler source file 	NGC
NIF
	netimmerse/gamebyro file
NIL
	NIL 	Icon Hear-It
NITF
	National Imagery Transmission Format 	
NK2
	e-mail address autocomplete archive 	Microsoft Office Outlook
NL
	Norton Desktop Icon Library 	
NLM
	Netware loadable module 	Novell Netware
NLS
	National Language Support file 	MS-DOS
NLX
	Form 	FormWorx 3.0
nnn
	Arj archive volumes up to 999 	ARJ
nnn
	Netware unicode rule table (e.g. 1250_Uni.036) 	Novell Netware
nnn
	News about smth with ext. of ver. number 	
nnn
	RAR archive volumes up to 999 	RAR
NOT
	Notation 	
NOT
	Yard Notes File 	FYM
NP
	Project schedule (Nokia Planner) 	Nokia Planner
NPI
	Source for DGEN.EXE interpreter 	dBASE Application Generator
NPJ
	Nile Project 	Game Mission Editor
NRG
	Nero Disc Image File 	Nero Express / Burning ROM
NRW
	Nikon Coolpix RAW image 	Nikon
NSA
	media 	Nullsoft Streaming Audio
NSF
	database 	Lotus Notes
NSS
	Norton screensaver module 	NC - NDW Screen Saver
NST
	Music module 	Amiga Noise Tracker
NSV
	media 	Nullsoft Streaming Video
NSX
	Compound index file 	SuccessWare SIX 3.00
NT
	Startup files 	Windows NT
NTF
	database design template 	Lotus Notes
NTH
	Nokia Theme File 	Nokia PC Suite
NTR
	Executable ASCII text file (strip header and rename) 	netrun31.zip
NTS
	Executable ASCII text file (strip header and rename) 	netsend1.zip
NTS
	Tutorial 	Norton
NTX
	Database index file 	Clipper 5
NUF
	Message for new users on their 1st call 	Procomm Plus
NUMBERS
	Numbers spreadsheet file 	Numbers (Apple iWork '08)
NWS
	Info text file (latest news) (ASCII) 	
NXT
	Sound (NeXT format) 	
[edit] O
Ext. 	Description 	Used by
O$$
	Outfile 	Sprint
O
	Object file 	UNIX - Atari - GCC
O01
	Typhoon vOice file 	AWAVE
OAZ
	Fax 	NetFax Manager
OB
	Object cut/paste file 	IBM LinkWay
OBD
	Microsoft Office Binder 	MSOffice
OBJ
	Compiled machine language code 	
OBJ
	Object code 	Intel Relocatable Object Module
OBJ
	Wavefront Object 	
OBJF
	Data 	Triangle strips object
OBR
	Object browser data file 	Borland C++
OBS
	Script 	ObjectScript
OBT
	Microsoft Office Binder Template 	MSOffice
OBV
	Visual interface 	ObjectScript
OBZ
	Microsoft Office Binder Wizard 	MSOffice
OCF
	Object Craft File 	Object Craft
OCD
	OCAD Map File 	OCAD
OCR
	Incoming fax transcribed to text 	FAXGrapper
OCT
	Musical file 	Pctalizer
OCX
	New Custom Control's format in VB 4.0 	Visual Basic
OCX
	OLE custom control 	
ODB
	OpenDocument database 	OpenOffice.org Base
ODF
	OpenDocument formula 	OpenOffice.org Math
ODG
	OpenDocument drawing 	OpenOffice.org Draw
ODIF
	Open Document Interchange Format 	
ODL
	Object Description Language 	
ODL
	Type library source 	Visual C++
ODM
	OpenDocument master document 	OpenOffice.org Writer
ODP
	OpenDocument presentation 	OpenOffice.org Impress
ODS
	OpenDocument spreadsheet 	OpenOffice.org Calc
ODT
	OpenDocument text document 	OpenOffice.org Writer
OFD
	Form definition 	ObjectView
OFF
	Object File Format vector graphics file 	
OFF
	Object File Format vector graphics 	
OFM
	PostScript font description file 	
OFN
	Microsoft Office documents 	Microsoft Office
OGG
	Ogg multimedia container format
OHB
	Source 	On Hand Basic
OHS
	Outbound History 	Bink/+
OIF
	QuickBase file format
OKT
	Music (8 channels) 	Oktalyzer
OKT
	Music format 	Oktalyzer
OLB
	Object library 	VAX
OLD
	Backup file 	
OLI
	Text file 	Olivetti
OLSR
	Configuration file 	olsrd
OMA
	Audio file 	Labelgate CD 2, MAGIQLIP2
OOF
	Data 	Outrage 3D Object Format (Descent)
OOG
	Data 	WEBOOGL 3D object
OOM
	Swap file 	Shroom
OPJ
	Origin Project File 	Origin version 4.1 and later
OPN
	Active options 	Exact
OPT
	Options 	name used by many programs for configuration information
OPT
	Delphi project options 	Borland Delphi
OPT
	Optimize support file 	QEMM
OPW
	Organization chart 	Org Plus for Windows
OPX
	Inactive options 	Exact
ORA
	Parameter file 	Oracle
ORG
	Calendar file 	Lotus Organizer
ORG
	Older Origin Project 	Origin versions 4 or earlier
OTG
	OpenDocument drawing template 	OpenOffice.org Draw
OTB
	Over-the-air bitmap graphics 	
OTH
	OpenDocument HTML document template 	OpenOffice.org
OTL
	Outline font description 	Z-Soft Type Foundry
OTL
	Ventura Publisher's Type Foundry Outline Editor format 	
OTP
	OpenDocument presentation template 	OpenOffice.org Impress
OTS
	OpenDocument spreadsheet template 	OpenOffice.org Math
OTT
	OpenDocument text document template 	OpenOffice.org Writer
OTX
	Text file 	Olivetti Olitext Plus
OUT
	Output file 	
OV1
	Overlay file (part of program to be loaded when needed) 	
OV2
	Overlay file (part of program to be loaded when needed) 	TomTom Point of Interest
OVD
	Datafile 	ObjectVision
OVL
	Overlay file (part of program to be loaded when needed) 	
OVR
	Overlay file (part of program to be loaded when needed) 	
OXT
	OpenOffice.org extension 	OpenOffice.org
[edit] P
Ext. 	Description 	Used by
P
	Database PROGRESS source code 	PROGRESS
P
	PASCAL source code file 	
P
	Parser source code file
P
	Picture file 	APPLAUSE
P
	Rea-C-Time application parameter file 	ReaGeniX code generator
P0?
	Split archive UC2 	SAS.EXE
P10
	Tektronix Plot 	GCGW
P10
	Certificate Request 	
P12
	Personal Information Exchange 	"Crypto Shell Extensions"
P16
	Music (16 channels) 	ProTracker Studio 16
P22
	Patch file (Patch22) 	Patch22
P80
	PLM-80 source
P86
	PLM-86 source
p2v
	Backupfile of a project in eventplanning software plan2viz (windowsbased)
P3T
	Playstation 3 Theme file 	PS3 Theme settings menu
PA1
	Worktable 	PageAhead
PAC
	SBStudio II Package or Song 	SBStudio II
PAC
	STAD Image (graphics ?) 	
PACK
		
PACKAGE
	Content 	The Sims 2
PAD
	Automatic print definitions 	Produa
PAD
	Keypad definition 	Telemate
PAF
	For Personal Ancestral File data files
PAGES
	Pages document file 	Pages (Apple iWork '08)
PAK
	Archive 	Pak
PAL
	Palette file 	Microsoft Draw - Win. Paintbrush - many
PAL
	Palette file 	Diablo II
PAN
	Printer-specific file (copy to coreldrw.ink) 	CorelDRAW
PAR
	Parameter file 	Fractint
PAR
	PARTS application 	Digitalk PARTS
PAR
	Permanent output file 	Windows 3.x
PAR
	Parity Archive 	
PAR2
	Parity Archive v2 	
PART
	Part of a download file 	
PAS
	Pascal language source 	Borland Pascal
PAT
	Gravis Ultrasound Patch 	Convert (c) Villena
PAT
	Hatch patterns 	AutoCAD - Photostyler
PAT
	Vector fill files 	CorelDRAW
PAT
	Pattern File 	Photoshop
PAT
	GIMP pattern
PB
	Fax 	FAXability Plus
PB
	Phonebook 	WinFax Pro
PB
	Proboard Conf. files 	Proboard
PB
	Setup file 	PixBase
PB1
	Document 	First Publisher for Windows
PBA
	Powerbasic BASIC source code 	Genus
PBD
	Phone book 	FaxNOW! - Faxit
PBD
	Molecule (protein data bank) 	
PBI
	Powerbasic include file 	Genus
PBI
	Profiler Binary Input 	Microsoft Source Profiler
PBK
	Microsoft Network Phone book 	MSN
PBL
	Powerbasic library 	Genus
PBM
	PBM Portable Bit Map graphics format 	Jasc Media C.
PBM
	Planar bitmap graphics 	XLib
PBO
	Profiler Binary Output 	Microsoft Source Profiler
PBT
	Profiler Binary Table 	Microsoft Source Profiler
PC
	Text file containing IBM PC specific info 	
PC3
	Custom palette 	Harvard Graphics 3.0
PC8
	ASCII text IBM8 character set 	NewWave Write
PCA
	Perfect Clarity Audio 	Sony Vegas Pro
PCB
	P-CAD database 	P-CAD, PCBExpress, and other Printed Curcuit Board design software
PCB
	Artwork design file (Circuit board design) 	Zuken CadStar
PCC
	Cutout picture vector graphics 	PC Paintbrush
PCD
	Graphics format (Kodak Photo-CD) 	
PCD
	Kodak Photo-CD Image graphics file (768x512) 	hpcdtoppm
PCF
	Pixel Coordination Format
PCH
	Patch file 	
PCH
	Precompiled header 	Microsoft C/C++
PCJ
	Multimedia authoring tool graphics file 	IBM's Linkaway-Live
PCK
	Pickfile 	Turbo Pascal
PCL
	HP-PCL graphics data file 	HP Printer Control Language
PCM
	OKI MSM6376 synth chip PCM 	AWAVE
PCM
	PCM 	Authorware
PCS
	Microsoft PowerPoint picture package 	Microsoft PowerPoint - Microsoft ClipArt Gallery
PCT
	Bitmap graphics file 	Macintosh b&w PICT1 - color PICT2
PCW
	Text file 	PC Write
PCX
	PC paintbrush bitmap format 	QPeg - Display - ZSoft - PC Paintbrush
PDA
	Bitmap graphics 	
PDB
	Data 	TACT
PDB
	Packrat 5.0 data file 	Packrat 5.0
PDB
	Molecule (protein data bank) 	
PDD
	Adobe Photoshop Elements Image 	Adobe Photoshop Elements
PDE
	Pathology Data Exchange
PDE
	data 	PowerDesk Encrypted
PDF
	Adobe's Portable Document Format 	Adobe Acrobat Reader
PDF
	Graphics file (ED-SCAN 24bit format) 	
PDF
	Package Definition File 	
PDF
	PCAD Database Interchange Format 	Pdifin.exe - Pdifout.exe
PDF
	Print device information Netware 	
PDG
	Print Shop Deluxe data file 	
PDI
	Portable Database Image 	
PDL
	Project Description Language file 	Borland C++ 4.5
PDM
	Program 	Deskmate
PDM
	PowerDesigner's physical data model (relational model) file format 	PowerDesigner
PDM
	Visual Basic (VB) Project Information File 	Visual Basic
PDN
	Image file 	Paint.NET
PDS
	PALASM Design Description 	
PDS
	Pds graphics 	
PDS
	Planetary Data System Format 	
PDS
	Pldasm source code file (hardware assembly) 	
PDV
	Printer driver 	Paintbrush
PDW
	Document 	Professional Draw
PEB
	Program Editor bottom overflow file 	WordPerfect Library
PED
	Program Editor delete save 	WordPerfect Library
PEM
	Program Editor macro 	WordPerfect Library
PEQ
	Program Editor print queue file 	WordPerfect Library
PER
	Program Editor resident area 	WordPerfect Library
PES
	Program Editor work space file 	WordPerfect Library
PET
	Program Editor top overflow file 	WordPerfect Library
pet
	package[2] 	Puppy Linux
PEX
	Proboard EXecutable file (Executed from PB) 	Proboard
PFA
	PostScript Font File 	
PFA
	Type 3 font file (unhinted PostScript font) 	
PFB
	Adobe Acrobat document 	Adobe Acrobat Reader
PFB
	PostScript font 	Adobe Type Manager (ATM)
PFC
	(Personal File Cabinet) contains e-mail, preferences and other personal information 	AOL
PFC
	Text file 	First Choice
PFK
	Programmable function keys 	XTreePro
PFM
	Windows Type 1 font metric file 	
PFS
	Database (PFS:FILE) - text file (PFS:Write) 	PFS
PFT
	Printer font 	ChiWriter
PG
	Page cut/paste file 	IBM LinkWay
PGI
	Printer Graphics File device driver 	PGRAPH library
PGL
	HP Plotter vector graphics format 	
PGM
	Graphics format (Portable GrayMap) 	JASC Media C.
PGM
	Program 	Signature
PGP
	Support file 	Pretty Good Privacy RSA System
PGS
	Manual page 	man4dos
PH
	Optimized .goh file 	Geoworks
PH
	Perl header file 	
PH
	Phrase-table 	Microsoft C/C++
PHD
	PolyHedra Database 	
PHM
	Phone book 	DN - Lync
PHN
	Phone list 	UltraFax - QmodemPro
PHO
	Phone database 	Metz Phone for Windows
PHP
	PHP file 	
PHP3
	PHP 3 file 	
PHP4
	PHP 4 file 	
PHR
	Phrases 	LocoScript
PI2
	Portrait Innovations High Resolution Encrypted Image file 	Portrait Innovations Studio2 (proprietary)
PIC
	123 Vector graphics format 	CShow - Alchemy - Paint (Pictor)
PIC
	Bitmap graphics file 	Macintosh b&w PICT1 - color PICT2
PIC
	Lotus picture 	
PIC
	PIXAR picture file 	SDSC Image Tool
PICT
	Macintosh Picture 	
PIE
	GlovePIE script file 	GlovePIE
PIF
	OS/2 graphics metafile 	PICVIEW.EXE
PIF
	Program Information File 	Windows 3.x
PIF
	Vector graphics GDF format file (IBM mainframe computers) 	
PiM
	Pascal Text Mode Image File 	The Ultimate Draw
PIT
	Compressed Mac file archive created by PACKIT 	unpackit.zoo
PIV
	Pivot Stick Animator file 	Pivot Stick Animator
PIX
	Alias image file 	SDSC Image Tool
PIX
	Inset Pix 	
PJ
	Project 	CA-SuperProject
PJT
	Additional (FPT) project description file 	FoxPro
PJX
	Main (DBF) project description file 	FoxPro
PK
	PacKed bitmap font bitmap file (TeX DVI drivers) 	
PK
	Peak file 	Cool Edit
PK2
	Quake 2 data file 	id Software
PK3
	Quake 3 data file 	id Software
PK4
	Doom 3 and Quake 4 data file 	id Software
PKA
	Archive 	PKARC
PKG
	Installer script 	Next, Mac OS X, Sony PS3
PKG
	P-CAD database 	P-CAD
PKT
	Fido message packet 	FTN software
PL
	Palette 	Harvard Graphics
PL
	Perl source code file 	
PL
	Prolog source code file 	
PL
	Property List font metric file 	TeX
PL1
	Room plan 	3D Home Architect
PL2
	Palette 	Diablo II
PL3
	Chart palette 	Harvard Graphics 3.0
PLA
	Playlist
PLB
	FoxPro library 	FoxPro
PLB
	P-CAD library 	P-CAD
PLC
	Add-in file (functions - macros - applications) 	Lotus 1-2-3
PLC
	P-CAD database 	P-CAD
PLD
	PhotoLine Document 	PhotoLine image processing
PLE
	Encrypted Chat Log 	Messenger Plus! Live Plugin - Log viewer
PLIST
	Mac OS Property List 	Apple's Property List Editor
PLL
	Prelinked library 	CA Clipper
PLM
	DisorderTracker2 music module 	AWAVE
PLN
	Spreadsheet 	WordPerfect for Win
PLP
	Playlist
PLP
	Messenger Plus! Sound Pack 	Messenger Plus! Live Plugin
PLS
	Playlist file 	WarpVision (OS/2)
PLSC
	Messenger Plus! Script Pack 	Messenger Plus! Live Plugin
PLSK
	Messenger Plus! Skin Pack 	Messenger Plus! Live Plugin
PLT
	HPGL plotter file vector graphics 	AutoCAD
PLT
	Output file for ploter 	
PLT
	P CAD: Output file editor for PCPLOT or PCPRINT 	P CAD
PLT
	Page Magic 2.0 paper format 	Page Magic 2.0
PLT
	Palette 	
PLT
	Table for .pll 	CA Clipper
PLY
	Data 	PopMail
PLY
	Presentation screen 	Harvard Spotlight
PLY2
	Data 	PLY2 object
PLY
	ZipPack 	
PM
	Auran Jet progressive mesh file (obsoleted by IM and LM) 	Trainz
PM
	Perl module 	
PM
	Bitmap graphics 	Presentation Manager
PM3
	PageMaker 3.0 data file 	PageMaker 3.0
PM4
	Document 	PageMaker 4
PM5
	Aldus PageMaker 5.0 publication 	Aldus PageMaker
PMC
	Graphics 	A4TECH Scanner
PMI
	OS/2 V3 SVGA PMI-File 	Svga.exe
PMI
	PhatPad note 	PathWare
PMM
	Program file 	Amaris BTX/2
PMP
	PhotoMorph Project 	PhotoMorph
PN3
	Printer device driver 	Harvard Graphics 3.0
PNG
	Portable Network Graphics 	
PNF
	Pre-compiled Setup Information file 	Microsoft Windows
PNM
	PBM Portable aNy Map graphics file 	
PNT
	Macintosh painting 	
PNT
	Pointlist segment 	FTN software
PNT
	QWK reader pointer file 	MarkMail 2.x
POH
	Optimized .goh file 	Geoworks
POL
	InnovMetric Software Polygon Models Format 	
POLICY
	Group Policy File 	Microsoft Windows
POLY
	Data 	Patrick Flynn's Poly Format - 3D object
POP
	Messages index 	PopMail
POP
	Pop-up menu object 	dBASE Application Generator
POT
	Microsoft PowerPoint template
POV
	Raytraced graphics image 	Persistence Of Vision
POW
	Power Chords instrument/song file 	Power Chords
PP
	Amiga archive 	POWERPACKER
PPA
	Microsoft PowerPoint Add-in
PPB
	Button bar for Print Preview 	WordPerfect for Win
PPD
	PostScript printer description file 	
PPJ
	Premiere Project 	Premiere
PPK
	Archive (using for many distributives) 	PPK
PPL
	PolaroidPalettePlus ColorKey device driver 	Harvard Graphics 3.0
PPM
	Graphics format (Portable PixelMap) 	JASC Media C.
PPO
	Preprocessor output 	CA Clipper 5.*
PPP
	Publication 	PagePlus
PPS
	Storyboard 	Personal Producer
PPS
	Microsoft PowerPoint Slideshow (stand alone slideshow)
PPT
	Microsoft PowerPoint Presentation 	Microsoft PowerPoint
PPTX
	Office Open XML Presentation
PR1
	Packrat 4.0 data file 	Packrat 4.0
PR2
	Packrat 4.x data file 	Packrat 4.x
PR2
	Presentation 	Aldus Persuasion 2.x
PR2
	Printer driver 	dBASE IV
PR3
	PostScript printer driver 	dBASE IV
PR3
	Presentation 	Aldus Persuasion 3.x
PRD
	Printer driver 	
PRE
	Presentation 	Freelance Graphics
PRE
	Settings 	Programmer's WorkBench, Microsoft C/C++
PRE
	Stork graphic file 	
PRF
	CheckIt Pro v1.0 data file 	CheckIt Pro 1.0
PRF
	Pixel Run Format graphics file 	Improces - Fastgraph
PRF
	Printer driver 	dBASE IV
PRF
	Profiler output 	
PRG
	Program source code (e.g. Clipper language) 	CA Clipper
PRG
	Program source 	dBASE IV - FoxPro - Clipper 5 - dBFast
PRG
	Program 	Atari
PRI
	Printer definitions 	LocoScript
PRJ
	Borland C++ IDE project file 	BC.EXE - BCW.EXE
PRK
	SimPark Saved File 	SimPark
PRM
	Parameters 	
PRN
	Printer driver 	Signature
PRN
	Text file 	Lotus 1-2-3 - Symphony
PRN
	Usually printer output file 	
PRO
	Profile 	used by many programs to store configuration data
PRO
	Graphics profile file 	DOS
PRO
	Proboard conf. file 	Proboard
PRO
	Prolog language source 	
PRO
	PROLOG source code file 	
PROJ
	Project File (Interface Builder) 	NeXT
PROPERTIES
	Java properties file 	Java applications
PROTO
	Message specification 	Google Protocol Buffers
PRR
	The Perfect Resume data file 	Perfect Resume
PRS
	Norton Viewer DLL file 	
PRS
	Presentation 	Harvard Graphics Win
PRS
	Printer Resource eg. fonts 	WordPerfect for Win
PRS
	Procedure 	dBASE IV
PRT
	P-CAD component 	P-CAD
PRT
	Part or Drawing 	Cadkey
PRT
	Printer driver 	Dr. Halo
PRX
	Compiled program 	FoxPro
PS
	Document in PostScript format 	adobe
PSA
	Archive (Pretty Simple Archive) 	PSA.OUT (GNU)
PSD
	Periscope Debbuger Def file 	Periscope
PSD
	Photoshop bitmap file 	Photoshop document
PSE
	see PSEG 	
PSEG
	Bitmap graphics 	IBM printer Page SEgment
PSF
	Outline PostScript printer font 	ChiWriter
PSM
	Music format (Protracker Studio Module) 	Protracker - MASI
PSM
	Symbol table of IDE 	Turbo Pascal
PSM
	3D Model 	18 Wheels Of Steel
PSN
	Presentation file for Sound Script 	Win
PSP
	image file with layers 	Paint Shop Pro (all versions)
PSQ
	Premiere Sequence 	Premiere
PST
	Postbox file 	BMail
PST
	Archive File 	Microsoft Outlook
PSV
	Playstation 2/Playstation 3 saved game 	Playstation 2 and Playstation 3
PSW
	File w/ passwords for any program/game 	many
PT
	Game crack 	Player Tools
PT
	Kodak Precition Color Management System 	
PT3
	Device driver 	Harvard Graphics 3.0
PT3
	Template 	PageMaker 3
PT4
	Template 	PageMaker 4
PT5
	Aldus PageMaker 5.0 publication template 	Aldus PageMaker
PTB
	Power Tab Software 	Power Tab Editor
PTB
	Script 	PubTech BatchWorks
PTF
	Playstation Portable Theme file 	PSP Theme settings menu
PTF
	ProTools Session File 	Digidesign ProTools
PTG
	Panasonic Title Graphics
PTL
	Premiere Title 	Premiere
PTM
	Macro 	PubTech BatchWorks
PTM
	Music format 	
PTM
	Page Magic 2.0 template 	Page Magic 2.0
PTN
	Pattern 	Cadkey
PTN
	Pattern 	CarveWright/CompuCarve Designer
PTR
	OS/2 cursor image file 	ICONEDIT.EXE
PTR
	QWK reader pointer file 	QMail
PTU
	Performer Terrain Utilities 	
PUB
	Package File 	Exstream Dialogue
PUB
	Page template 	Microsoft Publisher
PUB
	Public key ring file 	Pretty Good Privacy RSA System
PUB
	Publication 	Ventura Publisher - 1st Publisher
PUD
	Warcraft II Map file 	Warcraft 2
PUT
	Archive 	PUT
PUT
	Graphics format 	WScan
PVD
	Script 	Instalit
PVL
	Library 	Instalit
PVM
	Texture Files 	PVMEdit
PVT
	Local Fidonet pointlist 	FTN software
PW
	Text file 	Professional Write
PWF
	Workflow Files 	Mac OS X Server Podcast Producer
PWL
	Password List 	
PWP
	Text document 	Professional WritePlus
PX
	Paradox 3.0 file 	Paradox 3.0
PXP
	3DS Process file 	3D Studio
PXR
	Pixiar Picio 	AltamiraComposer
PXZ
	Compressed file to exchange media elements 	PSALMO
PY
	Python script file 	Python interpreter
PYC
	Compiled Python module 	Python interpreter
PYI
	Cognos Powerplay Model 	
PYO
	Optimized compiled Python module 	Python interpreter
PZD
	Default settings 	Pizazz Plus
PZI
	Graphics format 	PZP
PZO
	Overlay file 	Pizazz Plus
PZP
	Palette 	Pizazz Plus
PZS
	Settings 	Pizazz Plus
PZT
	Transfer file 	Pizazz Plus
PZX
	Swap file 	Pizazz Plus
[edit] Q
Ext. 	Description 	Used by
Q0
	Q0 graphic file 	
Q3S
	Data 	Quick3D Scene
QAG
	Quick Access Group 	Norton Desktop
QAP
	Application 	Omnis Quartz
QB
	Tony Hawk's Pro Skater series scripting files
QBB
	Quickbooks Backup File
QBE
	Saved query (Query By Example) 	dBASE IV - Quattro Pro
QBO
	Compiled query 	dBASE IV
QBW
	Spreadsheet 	QuickBooks for Windows
QCH
	Qt Compressed Help 	Trolltech Qt Assistant
QDF
	Data file 	Quicken data file
QDK
	Backup of startup files created by Optimize 	QEMM
QDn
	Data file - segment n 	Omnis Quartz
QDV
	Graphics file 	Steve Blackstock Giffer
QDR
	Configuration file 	Q-Dir
QEF
	Query file 	Q+E for Microsoft Excel
QFX
	Quicken-specific implementation of the OFX specification 	Intuit Quicken
QFX
	Fax 	QuickLink
QHC
	Qt Help Collection 	Trolltech Qt Assistant
QHCP
	Qt Help Collection Project 	Trolltech Qt Assistant
QHP
	Qt Help Project 	Trolltech Qt Assistant
QIF
	Quicken Interchange Format 	Intuit Quicken
QIZ
	World book quiz 	World Book
QLB
	Quick library 	Microsoft C/C++
QLC
	ATM Type 1 fonts script 	Adobe Type Manager
QLP
	Printer driver 	QuickLink
QM4
	Options or services file 	QMail 4.x Mail Door
QPR
	Generated query program 	FoxPro
QPR
	Print queue device driver 	OS/2
QPX
	Compiled executable QBE query file 	FoxPro
QRS
	Equation Editor support file 	WordPerfect for Win
QRT
	Graphics format (QRT ray tracing) 	
QRY
	Query 	dBASE IV
QT
	QuickTime movie (animation) 	
QTVR
	QuickTime VR Movie 	
QVD
	QlikView Document (Data) 	QlikView Compressed Database File
QVW
	QlikView Document (View) 	QlikView Presentation File
QWK
	QWK reader message file 	
QXD
	Document 	QuarkXPress
QXL
	Element library 	QuarkXPress
[edit] R
Ext. 	Description 	Used by
R
	Ratfor file 	
R
	Script file 	R
R00, R01, ...
	Part of a multi-file RAR archive.
R2D
	Reflex 2 datafile 	Reflex 2
R8
	Raw graphics file (one byte per pixel) plane one 	PicLab
R8P
	PCL 4 bitmap font file 	Intellifont
RA
	Remote Access conf. files 	RA
RA0, RA1, ...
	Part of a multi-file RAR archive. 	
RAD
	2-op FM music 	Reality AdLib Tracker
RAD
	Radiance 	
RAL
	Remote Access Language file 	Remote Access
RAM
	Ramfile 	RealAudio
RAR
	Archive 	RAR
RAS
	Graphics format 	SUN Raster
RAT
	Datafile (RATS) 	
RAW
	HSI raw graphic file 	
RAW
	PCM Signed Raw Sound File 	
RAW
	QRT graphic file 	
RAY
	Rayshade 	
RB
	Ruby Script file 	
RBF
	Datafile 	Rbase
RC
	Configuration file 	emacs
RC
	Resource Compiler script file 	Microsoft C/C++, Borland C++
RC
	Resource Script 	Resource Writer
RC
	UUPC configuration files 	UUPC
RC
	Windows resource compiler script 	RC.EXE -Resource WorkShop - OS/2
RCG
	Netscape newsgroup file (netsc.rcg) 	
RData
	Data file 	R
RDF
	Compiled UIC source code 	Geoworks UI Compiler
RDI
	Device-independent bitmap file (RIFF RDIB format) 	
RDP
	RDP connection 	Remote Desktop connection
RDX
	Datafile 	Reflex
REC
	Archivation protocol 	ARCSERVE
REC
	Datafile 	EpiInfo
REC
	Record file 	Sprint
REC
	Windows Recorder Macro File 	WinRecorder
RED
	Path info 	Clarion Modula-2
RED
	REDuced nodelist file 	T-Mail nodelist Compiler
REF
	Cross-reference 	
REG
	OLE Registration file 	Windows 3.x
REG
	Registration information or key 	
REL
	Foreground job relocatable file 	RT-11
REM
	Remarks definition 	Sourcer
REM
	Remarks 	
REP
	QWK reader reply file 	
REP
	Report file used by many applications 	
REP
	Report 	Report Designer - CodeReporter - DataBoss
REQ
	File request 	FTN Software
RES
	Compiled resource 	Microsoft C/C++, Borland C++
RES
	DBASE resources 	dBASE IV
RES
	Windows compiled resource package 	Win
REV
	Revision file 	Geoworks
REX
	PharLab executable file (old format) 	PharLab
REX
	Report definition 	Oracle
REX
	Rexx language source file 	Rexx
REZ
	Resource file 	
RF
	Sun raster graphics file 	
RFT
	DCA/RFT Revisable Format Text file 	IBM DisplayWrite 4.0-5.1
RGB
	SGI RGB image file (RAW) 	SDSC Image Tool
RGX
	Symbol tables etc. info 	ReaGeniX code generator
RH
	Resource header file 	Borland C++ 4.5
RH
	Windows resource file header 	RC.EXE
RHistory
	Command history logfile 	R
RI
	Data 	Lotus 1-2-3
RIB
	Graphics (Renderman Interface Bytestream) 	3D Reality
RIC
	Fax 	Ricoh
RIF
	RIFF bitmap graphics (Resource Interchange File Format) 	Fractal Design Painter
RIP
	TeleGrafix Remote Imaging Protocol 	Maximus 3.0
RIX
	Graphics (ColoRIX Image File) 	ColoRIX
RL4
	Bitmap graphics 	
RL8
	Bitmap graphics 	
RLA
	Wavefront raster image file 	SDSC Image Tool
RLB
	Data hgw.rlb 	Harvard Graphics Win
RLC
	Graphics 1bit/pixel scanner output 	
RLD
	Norton Commander 5.0 temp file 	NC 5.0
RLD
	OSIMapDef. RecLoad Definition 	
RLE
	Utah Run Length Encoded rasterfile graphic file 	SDSC Image Tool
RLZ
	REALIZER source code file 	CA-Realizer
RM
	Real Media 	Real Player
RMB
	data 	RegistryMaster
RMI
	Windows alternate synthesized sound format 	RIFF RMID format
RMK
	Make file 	CA Clipper - RMAKE
RMVB
	Real Media Variable Bitrate 	Real player
RN
	XPL program for Nota Bene users 	
RND
	Rendering Slide 	AutoCAD AutoShade
Rnn
	Multi volume RAR archive 	RAR
RNO
	Runoff file 	VAX
ROL
	FM music Adlib Music File 	Roland
ROM
	Read Only Memory image in emulators, AONs, etc. 	
ROO
	CODASYL DBMS Database Root 	Oracle
RPB
	Data report file used by CP Backup 	CP Backup
RPD
	Database 	RapidFile
RPF
	AutoCAD pattern 	ACAD
RPL
	Text document 	Replica
RPM
	Red Hat Package Manager (Command line driven package management system capable of installing, uninstalling, verifying, querying, and updating computer software packages in Red Hat Linux) 	Red Hat Linux
RPT
	Report file used by many applications 	
RRD
	Reduced Resolution Dataset 	ESRI (GIS)
RS
	Data file 	Amiga Resource - Reassembler
RS_
	Resource fork of a Macintosh file 	Mac-ette
RSC
	Resource file 	ViewMax - many
RSL
	Application - Project 	resolver one
RSL
	Resource Library used by PC Tools for Windows 	PC Tools - Win
RSP
	Response file (text file containing input expected by eg. LINK) 	
RSP
	Response File 	OS/2
RSY
	FLEXIT Multishot Survey Raw Data file 	FLEXIT
RTF
	Rich Text Format text file (help file script) 	many - Microsoft Word
RTFD
	RTF-Packet 	NeXT
RTL
	HP RTL graphic file 	
RTL
	Run-Time library 	Norton Utilities
RTL
	Text file 	
RTP
	RTPatch software update package data file 	Pocket soft patch
RTS
	Realizer executable file 	
RTS
	Runtime library file 	CA-Realizer
RUL
	Echo-conference rules 	
RUN
	PC Tools for Windows batch file 	PC Tools
RUNZ
	pseudo-executable file, used in Portable Apps and software installers for Super OS 	RUNZ Framework
RUS
	Russian text 	
RV
	Mobile pricelist data file 	Mobile
RVF
		TRichView
RVW
	Review 	
RWS
	Borland Resource Workshop symbol file 	Resource Workshop
RWS
	Resource Workshop data file 	Borland C++
RWX
	Criterion RenderWare 	
RWX
	MEME Shape File 	
RWX
	Script 	RenderWare
RWZ
	Microsoft Outlook Rules Wizard File 	Microsoft Outlook
RXD
	Reflex 1 datafile 	Reflex 1
RZK
	File Crypt password file 	All text editors
RZX
	File Crypt encrypted file 	File Crypt (Akte Krypta, Kriptirnik)
[edit] S
Ext. 	Description 	Used by
S$$
	Temporary sort file 	Sprint
S
	ASSEMBLY source code file 	unix
S
	Multi Edit macro file source 	Multi Edit
S
	MSTS Shape file 	MSTS
S19
	Motorola ASCII format of executables
S1K
	S1000 Simnet Format 	
S3I
	Digiplayer/ST3 Sample File 	Digiplayer - ST3
S3M
	Music (16 channels) 	Scream Tracker 3.0 - DMP
S7I
	Seed7 library / include file 	Seed7 interpreter and compiler
SA?
	Packed mail 	FTN software
SAB
	Saber file 	Star Wars: Jedi Knight Jedi Academy
SAF
	see SAIF 	
SAFE
	SafeIT Encrypted
SAIF
	Spatial Archive Interchange Format 	
SAL
	Datafile 	SORITEC
SAN
	LucasArts' SMUSH/INSANE animation
SAM
	Ami Pro data file 	Ami Pro
SAM
	Text file 	Samna - Lotus Ami/Ami Pro
SAR
	Archive 	SAR
SAT
	ACIS 	
SATS
	Static source 	ATS
SAV
	Backup file (saved file) 	
SAV
	Configuration 	
SAV
	Executable 	RT-11
SAV
	SPSS "System File" 	PSPP
SAV
	Saved game state 	Spider Solitaire (Windows)
SAVER
	Screensaver 	Mac OS X
SB
	Audio file (signed byte) 	
SB
	Raw Signed Byte (8bit) data 	AWAVE
SB
	Raw Signed PCM Byte 8bit data 	AWAVE
SBD
	Storyboard 	Storyboard Editor
SBI
	Sound Blaster Instrument file (Creative Labs) 	
SBK
	Emu SoundFont Bank (AWE32 Bank) 	Convert (c) Villena
SBL
	Stony Brook Pascal library 	SB Pascal
SBP
	DML program 	Superbase 4
SBR
	Support file 	Source Browser
SBT
	Notes related to record 	Suberbase 4 Windows
SC
	Display driver 	Framework II
SC
	PAL script 	Paradox
SC
	Script 	Borland Paradox
SC3
	Renamed dBASE III screen mask file 	dBASE IV
SC3
	Screen device driver 	Harvard Graphics 3.0
SC4
	Saved City 	SimCity 4
SC4
	Game Scenario 	RollerCoaster Tycoon Deluxe/Expansion Pack
SCA
	Datafile 	SCA
SCC
	Text file 	
SCD
	SCODOL film recorder (Scan Conversion Object Description Language) 	SCODOL
SCF
	Standard Chromatogram Format 	Staden package
SCF
	? 	SimAnt or SimTown ??
SCF
	Windows Explorer Command (e.g.: show desktop.scf) 	Windows Explorer
SCF
	Multimedia show 	ScoreMaker
SCF
	Spelling checker configuration file 	Symphony
SCH
	Project schedule 	Schedule Publisher
SCH
	Circuit Design Schematic 	P-CAD - Orcad - Protel
SchDoc
	Circuit Design Schematic 	Protel - Altium Designer
SCI
	Fax 	SciFax
SCI
	System Configuration Information 	
SCM
	Scheme source code file 	
SCM
	Schematic file (Circuit Diagram for PCB design) 	Zuken CadStar
SCM
	Starcraft mission 	
SCN
	SCeNe RTrace 	
SCN
	Screen file 	Kermit
SCO
	High score 	
SCP
	Script 	BITCOM
SCR
	Any other screen system 	
SCR
	DEBUG source code file 	DOS Debug
SCR
	Forth screen (source) file 	Forth
SCR
	Screen - screen snapshot 	dBASE IV - Procomm Plus
SCR
	Screen font 	LocoScript
SCR
	Screen saver 	Windows 3.x
SCR
	Screen snapshop 	
SCR
	Script file source 	TeleMate - Kermit - 1st Reader
SCT
	Additional (FPT) screen description file 	FoxPro
SCTOR
	Raster graphics format used by some very obscure custom operating systems. 	
SCX
	Chart 	Stanford Chart
SCX
	Graphics format 	ColoRIX
SCX
	Main (DBF) screen description file 	FoxPro
SCX
	Starcraft: Brood War scenario 	
SCY
	Security file 	ReaGeniX
SD
	Sound Designer I audio file 	AWAVE
SD7
	Seed7 source file 	Seed7 interpreter and compiler
SDA
	Fidonet's Software Distribution Network file archive description 	
SDC
	Video 	DigimaxMaster - Samsung NV3
SDC
	Synopsys Design Constraints 	Electronic Design Automation Tools
SDF
	Microsoft SQL Server Compact Edition database file 	
SDF
	Flight data 	microdrones GmbH
SDF
	Source definition file 	Sourcer
SDF
	System Data Format file (fixed length ASCII text) 	
SDI
	Software Distribution Network Info file 	
SDK
	Roland S-550/S-50/W-30 Disk Image 	
SDL
	Alias Wavefront Scene Description Language 	
SDM
	Signed Differential Mapping brain maps and/or distributions 	Signed Differential Mapping
SDML
	Spacial Data Modeling Language 	
SDN
	Software Distribution Network compressd file archive 	pak251.exe
SDR
	SmartDraw File 	SmartDraw Pro
SDS
	MIDI Sample DUMP Standard File 	
SDTS
	Spatial Data Transfer Standard 	
SDW
	Ami Draw Symbol File 	
SDX
	Sample DUMP Exchange File 	
SEA
	Self-Extracting compressed Macintosh file Archive 	
SEC
	compressed file 	
SEC
	Diskreet encrypted file 	Diskreet
SEC
	Secret key ring file 	Pretty Good Privacy RSA System
SEC
	Secured animation file 	Disney Animation Studio
SEN
	Scifer Archive Format ( Internal Header Mode] 	
SEP
	Printer separator page 	
SEQ
	ABI Text Sequence 	Applied Biosystems
SEQ
	Atari animation file 	
SEQ
	Video 	Tiertex video sequence
SEQ
	Sequential Instruction File 	Bubble Chamber
SES
	Session info 	Clarion Modula-2
SES
	Multitrack Audio Session info 	Adobe Audition
SET
	Configuration file 	1st Reader
SET
	Driver sets created by Install 	Symphony
SET
	Extension used by Norton Backup and CPS Backup for setup info 	Norton Backup - CPS Backup
SET
	Hump Assignments File 	FYM
SET
	Setup options file 	
SET
	YVD card set file 	YVD
SF
	IRCAM Sound File 	CSound package - MixView sound sample editor
SF
	JAR Digital Signature
SF
	WPS attribute storage (OS/2 WorkPlace Shell) wp_root.sf 	OS/2 WorkPlace Shell
SF2
	Emu SoundFont Bank v2.0 file 	AWAVE
SFB
	HP Soft font (obsolete under Windows) 	
SFD
	SoundStage Data file 	AWAVE
SFF
	Scene File Format 	
SFI
	Graphics 	SIS Framegrabber
SFI
	Printer font (HP LaserJet landscape) 	Ventura Publisher
SFL
	PCL 4 bitmap font (landscape) 	landscape - Intellifont -Ventura Publisher
SFN
	Font 	SPX
SFO
	Bitstream font file - fontware format 	
SFP
	PCL 4 bitmap font 	portrait - Intellifont - Ventura Publisher
SFR
	Sonic Foundry Sample Resource 	AWAVE
SFS
	PCL 5 scalable font file 	Intellifont
SFT
	Screen font 	ChiWriter
SFX
	SFX (self-extracting archives) script 	RAR
SG1
	Graphics 	Stanford Graphics
SGF
	Document with graphics 	Starwriter
SGI
	Graphics file 	IRIS - Silicon Graphics
SGP
	Statistics 	STATGRAPHICS Plus
SGT
	Save/get keyboard macro 	Signature
SH
	ASCII archive 	SHAR
SH
	Unix shell script 	
SH3
	Presentation 	Harvard Graphics 3.0
SHAR
	Archive 	UNSHAR (Unix)
SHB
	Background 	CorelShow
SHG
	Segmented Hyper Graphics 	Microsoft's shed.exe, JGsoft's Hotspot Builder, EC Software's Help and Manual
SHK
	Apple II archive 	SHRINKIT
SHM
	Shell macro 	WordPerfect Library
SHP
	Shape file and source file for text fonts

ESRI shapefile
	AutoCAD

ArcGIS
SHR
	see SHAR 	
SHT
	HTML format for WWW 	NetScape
SHW
	Presentation 	Harvard Graphics 2.0 - CorelShow
SHW
	Slide show 	WordPerfect Presentations
SHX
	Shape entities

ESRI shapefile
	AutoCAD

ArcGIS
SIB
	Sibelius file 	Sibelius 1-5
SIF
	Setup Installation Files info 	Windows NT Setup
SIG
	Current program settings 	Signature
SIG
	Signature file 	ThunderByte AntiVirus - PopMail
SIK
	Backup file (Sicherungskopie) 	Microsoft Word
SIM
	Simon document file - Simon instruction software editor
SIS
	symbian file
SIT
	Archive (Macintosh) 	STUFFIT
SKP
	Google SketchUp file 	
SKY
	SYLK Spreadsheet file (used by Multiplan) 	
SL
	S-Lang source code file 	
SLB
	P-CAD library (symbols) 	P-CAD
SLB
	Slide library 	AutoCAD
SLC
	SALT (script from Telix) compiled code 	Telix
SLD
	Slide 	AutoCAD
SLDPRT
	Part 	SolidWorks
SLDASM
	Assembly 	SolidWorks
SLDDRW
	Drawing 	SolidWorks
SLI
	Slide 	MAGICorp Slide Service
SLK
	Microsoft Excel import format 	Microsoft Excel
SLK
	SYLK Symbolic Link format data file 	MultiPlan
SLL
	Sound data file 	
SLP
	SLP command file created by SRCCOM 	RT-11
SLP
	Localization project file 	Sisulizer
SLT
	SALT Script Application Language for Telix script source 	Telix
SLV
	Solution for any game 	many
SM
	Maillist 	SoftSpoken Mailer
SM
	Script 	ScriptMaker
SM
	SMALLTALK source code file 	
SM
	Text file 	Samna Word
SM
	StepMania Step File 	StepMania
SMC
	Super Nintendo ROM 	
SMF
	Fax 	SMARTFAX
SMK
	Smacker Video Format (RAD Video) 	
SML
	System Macro Library 	RT-11
SMM
	Ami Pro Macro File 	Ami Pro
SMN
	Font (ParaGraph's WorkScript format) 	
SMP
	Sample (sound file) 	
SMP
	Samplevision File 	Samplevision
SMPL
	Data 	Megahedron 3D object
SMS
	MSTS Sound managemant system file 	MSTS
SMT
	Text file 	Smart Ware II
SN
	Compressed song file 	Sound Club editor
SND
	Digitized sound file 	Macintosh/ATARI/PC
SND
	Power Chords drum sound file 	Power Chord
SNDB
	SQLNotes database 	SQLNotes
SNG
	Song (midi sound) 	Midisoft Studio - Prism
SNO
	SNOBOL4 source code file 	
SNP
	Book-shelf for .BOO 	READIBM
SNP
	Microsoft Access report snapshot
SNP
	Output video format from Computer Eyes equipment 	
SO
	shared object, dynamically linked library 	Unix
SOAR
	Soar Production file
SOL
	Solution eg. game walkthroughs 	
SOM
	Network serial numbers 	Quattro Pro
SOM
	Sort information 	Paradox
SON
	Song 	SBStudio II
SOU
	Temporary BATCH file 	RT-11
SOU
	SBStudio II Sound File 	SBStudio II
SOU
	Sound data (sound tool) 	
SP
	Archive (unix) 	SPLINT
SPC
	Program 	Microsoft Multiplan
SPC
	Temporary file 	WordPerfect for Win
SPC
	SNES SPC-700 Sound File 	Super Jukebox
SPC
	Spectroscopic data (scientific) 	Thermo Scientific
SPD
	Scalable font 	Speedo - Harvard Graphics 3.0
SPF
	Slide presentation file 	EnerGraphics
SPF
	data 	SQR Portable Format
SPG
	Glossary 	Sprint
SPI
	Graphics (Siemens and Philips scanner) 	
SPIFF
	Still Picture Interchange File Format 	
SPIN
	Spin source file 	Parallax Propeller Microcontrollers
SPL
	Archive 	SPLINT
SPL
	Customized printer driver 	Sprint
SPL
	Divided file segment 	Slice
SPL
	Personal spell dictionary 	Signature
SPL
	Print spooling file 	Windows 3.x
SPL
	Sample 	
SPM
	Data wp{wp}.spm 	WordPerfect
SPP
	Printer file 	Sprint
SPR
	Document letter 	Sprint
SPR
	Generated executable screen file 	FoxPro
SPR
	Sprite 	
SPR
	Story Board sprites 	
SPS
	Exported SyncBack profile 	SyncBack
SPS
	Screen driver 	Sprint
SPS
	SPSSx source code file 	VAX/VMS
SPT
	Data support file (MITAC disk/system management utility pack) 	MITAC disk/system management utility pack
SPT
	SPITBOL source code file 	
SPW
	Worksheet 	SigmaPlot
SPX
	Compiled executable screen file 	FoxPro
SPX
	Ogg Speex bitstream[3] 	Xiph.Org_Foundation
SQD
	Squish message base 	Squish
SQI
	Squish message base index 	Squish
SQL
	SQL language code 	Any SQL database
SQL
	Squish message base lastread pointers 	Squish
SQM
	Windows Live Messenger log file 	
SQN
	Note file 	SquareNote
SQZ
	Archive 	SQUEEZE
SQZ
	FOXPRO Squeeze file 	FOXPRO
SRC
	Source code 	Aurora Compiler
SRC
	Multi-edit source 	Multi-Edit
SRC
	Source 	DataFlex
SRF
	Sun Raster File graphics file 	
SRP
	Script 	QuickLink
SRT
	Subtitle format 	SubRip
SS
	Bitmap graphics 	Splash
SS
	Screen saver 	DN
SSC
	Celestia Solar System Catalog file 	Celestia
SSD
	Datafile 	SAS/PC
SSF
	Graphic file 	SnagIt Studio File/PC
SSG
	Saved game 	Simsig
SSP
	Datafile 	SAS Transport
SSR
	FLEXIT Singleshot Survey Raw Data file 	FLEXIT
SST
	AVHRR graphic file 	
SSV
	Spreadsheet viewer file 	
ST
	Instrument library 	Scream Tracker
ST
	SMALLTALK source code file 	Little Smalltalk
ST
	Stamp 	NeoPaint
STA
	Data file 	Statistica
STA
	Saved state 	Reflection 4.0
STA
	Stack 	Spinmaker Plus
STB
	Symbol table file 	RT-11
STB
	Stub library 	Genus GX Kernel
STC
	Celestia Star Catalog file 	Celestia
STC
	OpenOffice.org 1.*spreadsheet template 	OpenOffice.org Calc
STD
	State Transition Diagram graphic file 	Prosa
STD
	OpenOffice.org 1.*drawing template 	OpenOffice.org Draw
STF
	Archive 	SHRINKTOFIT
STF
	Setup Table File 	
STI
	OpenOffice.org 1.*presentation template 	OpenOffice.org Impress
STK
	eBook 	Starebook
STL
	Stereolithography Interface Format 	
STM
	Music format (4 channels) (Scream Tracker Module) 	ST - DMP
STM
	State Transition Diagram model file 	Prosa
STO
	Pascal stub OBJ file 	Genus GX Kernel
STP
	Subtitler Project 	Belle Nuit Subtitler
STR
	Gate3 table structure file 	
STR
	Structure list object file 	dBASE Application Generator 	
STR
	Playstation video file 	
STS
	Music format (Scream Tracker Song) 	ST 2.0-2.3
STS
	Project status info 	Microsoft C/C++
STU
	Studio Project 	Pinnacle Studio (video editing software)
STW
	Data file 	SmartTerm for Windows
STW
	OpenOffice.org 1.*text document template 	OpenOffice.org Writer
STX
	Electronic book 	SmarText
STX
	Music format 	
STX
	Tax form 	CA-Simply Tax
STY
	Ami Pro Template (Style); used by other programs for `styles` 	Ami Pro
STY
	Style library or sheet 	many
SU?
	Packed mail 	FTN software
SUB
	Subtitle format 	SubViewer; Author David Dolinski
SUI
	SUIT library 	Simple User Interface Toolkit
SUM
	Summary 	
SUN
	Sun rasterfile graphics file 	
SUO
	Solution User Options for Microsoft Visual Studio
SUP
	Supplementary dictionary 	WordPerfect for Win
SVD
	Autosave file for document 	Microsoft Word
SVG
	Autosave file for glossary 	Microsoft Word
SVG
	Scalable Vector Graphics, many
SVQ
	Music format 	
SVS
	Autosave file for style sheet 	Microsoft Word
SVW
	Super Video Windows 	Conversion Artist
SVX
	Interchange, 8SVX/16SV 	AWAVE
SVY
	FLEXIT Survey data 	FLEXIT
SW
	Raw Signed Word (16bit) data 	AWAVE
SWF
	Shockwave Flash 	Macromedia
SWG
	SWAG Pascal Snippets file 	SWAG
SWP
	Document backup 	Sprint
SWP
	Swap file 	
SWT
	Hump Routes File 	FYM
SXC
	OpenOffice.org 1.*spreadsheet 	OpenOffice.org Calc
SXD
	OpenOffice.org 1.*drawing 	OpenOffice.org Draw
SXG
	OpenOffice.org 1.*master document
SXI
	OpenOffice.org 1.*presentation 	OpenOffice.org Impress
SXM
	OpenOffice.org 1.*formula 	OpenOffice.org Calc
SXP
	3DS Process file 	3D Studio
SXW
	OpenOffice.org 1.*text document 	OpenOffice.org Writer
SY1
	SmartPix symbol library 	Ami Pro
SY3
	Harvard Graphics format 	
SY3
	Symbol file 	Harvard Graphics 3.0
SYD
	Backup of startup files created by QEMM (?) autoexec.syd 	
SYD
	Sysedit backup file 	Sysedit
SYG
	Monitor and handler files created by SYSGEN 	RT-11
SYM
	Compiler symbolic information file 	
SYM
	P-CAD component (symbols) 	P-CAD
SYM
	Precompiled headers 	Borland C++
SYM
	Program symbol table 	Power C, Microsoft ILink incremental linker
SYM
	Symbol file 	Harvard Graphics 2.0, Microsoft Windows SDK
SYN
	SDSC Synu image file 	SDSC Image Tool
SYN
	Synonym file 	Microsoft Word 5
SYS
	Datafile 	SYGRAPH - SYSTAT - SPSS/PC
SYS
	System file - device driver or hardware configuration info 	DOS
SYW
	Graphics file (symbol) 	Harvard Graphics Win
SYW
	Yamaha SY-85/SY-99 Wave File 	Convert (c) Villena
[edit] T
Ext. 	Description 	Used by
T
	Archive without compression (tape) 	tar
T
	TADS source 	
T
	Tester symbol table 	ReaGeniX code generator
T?H
	Turbo Help file (Pascal, C, Assembler, ...) 	Borland Thelp
T$M
	??? - Found in Windows (Vista) temp folder c:\windows\temp
T2B
	Bookeen Cybook thumbnail 	Cybook
T2L
	True2Life file format 	3D Internet content developers
T44
	Temporary file for Sort or Index 	dBASE IV
T64
	Program 	C64S emulator
TAG
	Query tag name 	DataFlex
TAH
	Help file for Turbo Assembler 	Borland C++
TAL
	Adobe Type Align 	Adobe
TAL
	Text illustration 	TypeAlign
TAP
	Tape file 	ZX Spectrum emulator by g.a.lunter
TAR
	Archive 	TAR
TAZ
	Archive 	WinZipNT - TAR - COMPRESS
TB
	Tab file (Virtual Desktop Tab) 	Tabbery
TB1
	Font file 	Borland Turbo C
TB2
	Font file 	Borland Turbo C
TBF
	Fax 	Imavox TurboFax
TBK
	FOXPRO template backup file 	FOXPRO
TBK
	Memo backup 	dBASE IV - FoxPro
TBK
	Toolbook 	Asymetrix ToolBook
TBL
	Short for Table 	used by many programs
TBL
	Aldus TableEditor file 	TableEditor
TBL
	Gate3 table file 	
TBL
	Graphics file (native format) 	PageMaker TableEditor
TBL
	Table of values 	OS/2
TBR
	Norton Desktop custom toolbar 	NDW
TBS
	Text elements ?? (Textbausteine) 	Microsoft Word
TBX
	Table 	Project Scheduler 4
TBZ
	Archive 	WinZipNT - TAR - Bzip2
TC
	Configuration 	Turbo C - Borland C++
TCH
	Help file 	Turbo C - Borland C++
TCL
	Tool Command Language source code 	Swat
TCT
	Drawing Template 	TurboCAD for Windows
TCW
	Native Drawing File 	TurboCAD for Windows
TD
	Config from Turbo Debugger 	Turbo Debugger
TD0
	Compressed diskette in a file 	Teledisk
TD2
	Configuration file 	Turbo Debugger for Win32
TDB
	Database 	TACT
TDDD
	Imagine Object File Format 	
TDF
	Speedo font file 	
TDF
	Typeface definition file 	Speedo
TDH
	Help file for Turbo Debugger 	Borland C++
TDK
	Keystroke recording file 	Turbo Debugger
TDR
	Contens of Arvid tape 	
TDS
	Symbol table 	Turbo Debugger
TDT
	Thumbnail data 	AVCHD
TDW
	Configuration file 	Turbo Debugger for Windows
TEC
	Data 	TECPLOT output
TEC
	TECO macro file ("compiled" form) 	TECO
TEF
	Fax 	Relisys TEFAX
TEL
	Host file 	Telnet
TEM
	Input template 	IconAuthor
TEM
	Turbo Editor Macro Language script 	Borland C++
TERM
	Terminal File 	
TES
	TECO macro file (source form) 	TECO
TET
	Tetris results 	DN
TEX
	Datasheet 	Idealist
TEX
	TeX text file 	Scientific Word - TeX
TEX
	Image 	Slimtex
TEXT
	Text file 	
TF
	Configuration 	Turbo Profiler
TFA
	Area file 	Turbo Profiler
TFC
	Catalogue file 	Tobi's Floppy Cataloguer
TFF
	self executing TansForm dialogue 	TansForm
TFH
	Help file for Turbo Profiler 	Borland C++
TFM
	Tagged font metric file 	Intellifont
TFM
	TeX Font Metric file 	TeX
TFS
	Statistical information 	Turbo Profiler
TG1
	Project file 	On Target
TGA
	Targa True Color bitmapped format 	Paint.NET
TGZ
	Archive 	WinZipNT - TAR - GNUzip
TH?
	Packed mail 	FTN software
THE
	Windows'95 Desktop Theme 	Microsoft Plus
THM
	Thumbnail or Theme File 	Picture Publisher, PhotoMagic, Canon Digital Cameras, and Sony Digital Cameras will create these Thumbnail files. Also using the same file extension is Sony Ericsson Theme File, for a cell phone.
THS
	Thesaurus dictionary 	WordPerfect for Win
TIB
	Acronis True Image Backup 	Acronis True Image
TIC
	FTN special file with assotiated file description 	ALLFIX
TIF
	see TIFF 	
TIFF
	TIFF (tagged image format file) bitmapped file 	Alchemy - PhotoStyler -PageMaker - CorelDRAW
TIL
	Fuzzy logic knowledge base 	Togai InfraLogic Fuzzy-C Compiler
TIS
	Tile set 	MahJongg 3.0
TJL
	Backup file 	VAXTPU editor
TLB
	Interoperability Type Library 	Win95
TLB
	Reference table 	Bubble Chamber
TLB
	Text library 	VAX
TLB
	Type library 	Visual C++
TLC
	Compiled Tool Command Language source code 	Swat
TLD
	Disk Image 	Teledisk
TLH
	Typelib Generated C/C++ Header 	Visual C++
TLP
	Project 	TimeLine
TM2
	Typical Meteorological Year data (new) 	Typical Meteorological Year
TMF
	Tagged Font Metric file 	WordPerfect for Win
TMF
	TiVo movie 	TiVo
TMO
	ZTG global optimizer default output file 	Zortech C++
TMO
	HandsHigh ThoughtManager Outline 	ThoughtManager Desktop
TMP
	Temporary file 	ALL PROGRAMS
TMS
	TeleMate compiled script 	TeleMate
TMY
	Typical Meteorological Year data (old) 	Typical Meteorological Year
TMY2
	Typical Meteorological Year data (new) 	Typical Meteorological Year
TOC
	Table Of Contents text file (ASCII) 	
TOK
	Borland C++ 4.x reserved word list 	BCW.EXE
TOPC
	TopicCrunch SEO Project file holding keywords, domain and search engine settings (ASCII) 	
TORRENT
	TORRENT File 	\u03bcTorrent
TOS
	Character file 	The Only Sheet
TOS
	Self-extracting file archive (Atari ST) 	
TP
	Session-state file 	Turbo Profiler
TP
	Turbo Pascal cfg file 	Turbo Pascal
TP
	TinkerPlots Document 	TinkerPlots and Fathom Dynamic Data Software. Documents contain data tables, graphs, text, pictures, etc.
TP3
	Template 	Harvard Graphics 3.0
TPB
	Downloadable PCL Soft font file backup 	HiJaak
TPC
	File produced when an inter-Topicscape topic link file is exported to Windows 	3D Topicscape
TPF
	Downloadable PCL Soft font file 	HiJaak
TPF
	Print data in EMF format 	ThinPrint
TPH
	Help file 	Turbo Pascal
TPL
	Resident units library 	Turbo Pascal
TPL
	Template file 	GoldEd -ITrack
TPL
	Template 	Harvard Graphics 2.0
TPOLY
	Data 	TPOLY 3D object
TPP
	Protected Mode Units 	Borland Pascal 7.0
TPU
	Borland Pascal DOS Mode Library 	Borland Pascal
TPU
	Command file (VAXTPU editor) 	VAXTPU editor
TPW
	Borland Pascal Windows Library 	Borland Pascal
TPW
	Session-state file 	Turbo Profiler for Windows
TPZ
	Archive 	TAR - GNUzip
TR
	Man page input suitable for troff -man 	cawf2.zip
TR
	Session-state settings 	Turbo Debugger for DOS
TR2
	Session-state settings 	Turbo Debugger for Win32
TRC
	Debug support file 	Power CTrace
TRE
	Directory tree file 	PC-Tools
TRD
	Datafile 	TrID file identifier filetypes definitions package
TRIA
	Data 	Greg Hood's ASCII Triangle
TRIB
	Data 	Greg Hood's Binary Triangle
TRIF
	Tiled Raster Interchange Format 	
TRK
	Track (i.e. video sequence), used by many games 	
TRM
	Terminal settings 	Windows 3.x
TRN
	Translation support file 	Quattro - Clarion
TRS
	Executable file 	Micrografx or password file
TRS
	WiSo Mein Geld 2007 	
TRS
	IBM Mainframe log file 	TRSMAIN
TRU
	True Basic source file 	
TRW
	Session-state settings 	Turbo Debugger for Windows
TRY
	Typical Meteorological Year data (variant) 	TRNSYS
TS
	Qt Linguist TS File 	Trolltech Qt Linguist
TSE
	Data 	Light Map Maker ASCII Scene
TSK
	Microsoft Multimedia Task Application 	Win95
TSM
	Turbo Assembler Manual 	TASM for OS/2
TST
	Printer test file 	WordPerfect for Win
TSV
	Tab Separated Values 	
TTF
	TrueType Font file 	
TU?
	Packed mail 	FTN software
TUD
	The Ultimate Draw file 	The Ultimate Draw
TUT
	Tutorial 	
TV
	Table view settings 	Paradox
TVF
	Table view settings 	dBASE
TVn
	Overflow file above insert point in Doc n 	WordPerfect for Win
TXF
	Tax eXchange Format 	
TXI
	Support file 	TeX
TXT
	Common name for ASCII text file 	
TXT
	Tab-Delimited Text File 	Microsoft Excel
TXW
	Yamaha TX-16W Wave File 	Convert (c) Villena
TY
	TiVo movie 	TiVo
TYM
	Time Stamp (PageMaker 4) 	PageMaker 4
TZ
	Archive 	TAR - COMPRESS
TZB
	Archive 	TAR - COMPRESS - BTOA
TZL
	Tanzzle pattern file 	Tanzzle
TZX
	Tanzzle image file 	Tanzzle
[edit] U
Ext. 	Description 	Used by
U3D
	Model file format 	Ultimate 3D
U3D
	Universal 3D 	Adobe Acrobat
U8
	Sample 	
UB
	Raw Unsigned Byte (8bit) data 	AWAVE
UC2
	Archive 	UC II
UCN
	New archive 	UC II
UCS
	Unknownsoft Service Pack (mainly for Shadow OS 2009) 	Unknownsoft Computer Systems
UDF
	Filter 	Photostyler
UDO
	Data 	Moray User Defined Object
UDW
	Raw Unsigned DWord data 	AWAVE
UE2
	Encrypted archive 	UC II
UFI
	data 	UFO CaptureV2 settings
UHA
	UHarc archive
UHS
	Universal Hint System (binary file) 	
UI
	Espire source code file 	Geoworks UI Compiler
UI
	Qt Designer's UI File 	Trolltech Qt Designer
UI
	User interface 	Sprint
UIF
	Long prompts for windows 	WordPerfect for Win
UIH
	Espire header file 	Geoworks UI Compiler
UL
	ULAW audio file 	
ULD
	Information about uploaded files 	Procomm Plus
ULF
	data 	MRF Mapping Tool Kit Universal List Format
ULT
	Music 	UltraTracker
UMB
	Backup file 	MemMaker
UNF
	Universal NES Image Interchange File Format 	
UNI
	Datafile 	Forecast Pro
UNI
	Music format 	UNIMOD - MIKMOD
UNIF
	Universal NES Image Interchange File Format 	
UNX
	Text file containing UNIX specific info 	
UOML
	UniqueObject Markup Language (UOML) is a XML-based markup language 	
UOP
	Uniform Office Format presentation 	
UOS
	Uniform Office Format spreadsheet 	
UOT
	Uniform Office Format text 	
UPD
	Update data 	dBASE
UPO
	Compiled update data 	dBASE
URL
	Internet Shortcut (URL) 	Windows Explorer
URT
	Utah Raster Toolkit 	
USE
	Log file 	
USP
	Printer font with USASCII extended character set 	PageMaker
USR
	User database file 	Procomm Plus - Turbo C++ tour
UT!
	datafile 	uTorrent
UTZ
	Mobile Phone Theme 	Sony Ericsson
UU
	Encoded file (ASCII) 	UUENCODE/UUDECODE
UUE
	Encoded file (ASCII) 	UUENCODE/UUDECODE
UW
	Raw Unsigned Word 16bit data 	AWAVE
UWF
	UltraTracker WaveSample 	UltraTracker
[edit] V
Ext. 	Description 	Used by
V
	Consistency check support file 	ReaGeniX code generator
V
	Main input file for an image 	Vivid 2.0
V8
	Covox 8bit file 	AWAVE
V10
	Data 	Gouraud Shaded Vectors
V2D
	Voucher design file 	Voucher management included in JFire (e.g. when printing a voucher)
VAI
	multimedia 	PhotoDub document
VAL
	Validity checks and referential integrity 	Paradox for Windows
VAL
	Values list object file 	dBASE Application Generator
VALA
	Sourcecode 	Vala
VAN
	Animation 	VistaPro
VAP
	Value Added Process 	NetWare 2.xx
VAP
	Dialogic indexed adpcm voice file 	VBASE/40
VAR
	Variable file 	IconAuthor
VB
	Visual Basic .Net source file 	Visual Basic .NET
VBPROJ
	Visual Basic .Net Visual Studio 2003 Project File 	Visual Studio .NET 2003
VBR
	Visual Basic Custom Control file 	Visual Basic
VBS
	VBScript script file 	VBScript
VBX
	Visual Basic eXtension 	Visual Basic
VBZ
	Visual Basic Setup Wizard Template 	Setup Wizard
VC6
	Graphite - 2D and 3D drafting 	Ashlar-Vellum
VC
	Include file with color definitions 	Vivid 2.0
VC
	Spreadsheet 	VisiCalc
VCA
	Visual Clip Art 	
VCD
	VideoCD 	
VCD
	VirtualDrive CD Image File 	
VCD
	VisualCADD Drawing File 	
VCR
	VCR drivers for Arvid 	
VCW
	Visual workbench information 	Microsoft Visual C++
VCX
	Spreatsheet 	VisiCalc Advanced
VDA
	Bitmap graphics 	
VDO
	Story Board video image 	Story Board
VDR
	Drawing 	ComputerEasy Draw
VEG
	Vegas Project 	Sony Vegas
VEW
	GroupWise for Windows 	Win
VEW
	View file 	Clipper 5 - Lotus Approach
VFA
	FontLab Database file 	FontLab
VFM
	Ventura Font Metrics file 	
VFM
	Voting Form 	Voter
VFN
	Voting Form for Customers 	Voter
VGA
	VGA display driver 	
VGA
	VGA display font 	
VGD
	VGA display driver 	Generic CADD
VGR
	Graphics file 	Ventura Publisher
VI
	LabVIEW Virtual Instrument 	LabVIEW
VI
	Graphics file 	Jovian Logic VI
VI
	Watcom editor script 	VI.EXE
VIC
	see VICAR 	
VICAR
	Graphics (Video Image Communication and Retrieval) 	
VID
	Bitmap graphics (YUV12C M-Motion Frame Buffer) 	
VID
	Graphics format 	Word&Deed
VID
	MS-DOS Shell Monitor file 	MS-DOS 5
VID
	Screen device driver 	Word
VIF
	see VIFF 	
VIFF
	Khoros Visualization Image File Format 	SDSC Image Tool
VIK
	Graphics format (VIKING) 	
VIM
	Vim script file 	Vim text editor
VINF
	data 	ReMPEG log file - frames info
VIR
	Virus or infected file 	
VIS
	VIS graphics file 	
VLM
	Virtual Loadable Module 	Netware
VM
	Virtual Memory file 	Geoworks
VMC
	Virtual memory configuration 	DOS/4GW PM 32X DOS Extender
VMDK
	Virtual Disk file 	VMware
VMF
	Font characteristics 	Ventura Publisher
VMG
	Nokia message file format 	Text Message Editor (Nokia PC Suite)
VMS
	Text file containing VMS specific info 	
VO
	Include file with object definition 	Vivid 2.0
VOB
	Video Object 	DVD-R, DVD-RW
VOC
	Sound format (Creative Lab's Sound File) 	PlayVoc
VOF
	Object folder 	VZ Programmer
VOP
	Visual Orangator Project
VOP
	Visual OTTHYMO Project
VOX
	Dialogic adpcm file 	AWAVE, CoolEdit
VP
	3DS Video posting 	3D Studio
VPF
	Vector Product Format 	
VPG
	Graphics file 	VPGraphics
VPH
	Virtual Pascal Help 	VP/OS2
VPI
	Virtual Pascal Unit 	VP/OS2
VQA
	Vector Quantized Animation 	The Legend of Kyrandia
VRM
	Overlay file 	QuattroPro
VRM
	Visual rexx source 	WATCOM VREXX
VRML
	Virtual Reality Modeling Language 	NetScape
VRP
	Project 	WATCOM VX?Rexx
VRS
	Video Resource eg. video device driver 	WordPerfect
VS
	Include file with surface definition 	Vivid 2.0
VSD
	Diagram 	Shapeware Visio
VSD
	Visio drawing 	Visio
VSM
	Simulation model 	VisSim
VSP
	Sprite 	SPX
VSS
	SmartShapes file 	Shapeware Visio
VSS
	Visio Template 	Visio
VST
	Truevision Vista graphics file 	
VST
	Visio Template 	Visio
VUE
	Animation 	3D Studio
VUE
	View 	dBASE IV - FoxPro
VW
	Text file 	Volkswriter
VWR
	File viewer file 	PC Tools
VWX
	CAD File 	VectorWorks 2008
VXD
	Windows 3.x virtual device driver 	Windows 3.x
[edit] W
Ext. 	Description 	Used by
W
	Word chart file 	APPLAUSE
W01
	Yamaha SY-series wave files 	AWAVE
W01
	Yamaha TX16W wave file 	AWAVE
W30
	Printer font 	AST TurboLaser - Ventura Publisher
W31
	Startup file 	Windows 3.1
W3A
	Warcraft 3 Abilities Export File 	Contained in a Warcraft 3 map
W3B
	Warcraft 3 Destructables Export File 	Contained in a Warcraft 3 map
W3D
	Warcraft 3 Doodads Export File 	Contained in a Warcraft 3 map
W3G
	Warcraft 3 Replay File 	File for Warcraft 3
W3H
	Warcraft 3 Buffs Export File 	Contained in a Warcraft 3 map
W3M
	Warcraft 3 Map 	File for Warcraft III: Reign of Chaos
W3N
	Warcraft 3 Campaign 	File for Warcraft III: The Frozen Throne
W3O
	Warcraft 3 Object Data Export File 	Contained in a Warcraft 3 map
W3P
	Warcraft 3 Save 	Save File for Warcraft 3
W3Q
	Warcraft 3 Upgrades Export File 	Contained in a Warcraft 3 map
W3T
	Warcraft 3 Item Export File 	Contained in a Warcraft 3 map
W3U
	Warcraft 3 Unit Export File 	Contained in a Warcraft 3 map
W3V
	Warcraft 3 Save 	Save File for Warcraft 3
W3X
	Warcraft 3 Expansion Map 	File for Warcraft 3: The Frozen Throne
W3Z
	Warcraft 3 Save 	Save File for Warcraft 3
W40
	Something for Windows95 (e.g. config.w40) 	Win95
W44
	Temporary file for Sort or Index 	dBASE
W95
	Something for Windows95 	Win95
WAD
	War Allocation Daemon 	Doom - Doom2
WAG
	Yard Contents File 	FYM
WAI
	Warcraft 3 AI Data File 	Warcraft 3 AI Data File
WAR
	Java Web Archive 	A Java file format used to package and deploy web applications.
WAS
	ProComm Script File (source code) 	ProComm
WAV
	Sound format (Microsoft Windows RIFF WAVE) 	Media Player
WAX
	ProComm compiled script 	ProComm
WB1
	Notebook 	Quattro Pro
WB2
	Spreadsheet 	Quattro Pro
WBF
	Microsoft Windows Batch File 	Catch
WBK
	Document/workbook or Microsoft Word backup file 	WordPerfect for Win or Microsoft Word
WBT
	Norton Desktop 	Norton Desktop
WBT
	Wilsonware Batch file 	Winbatch
WCD
	Condes Event Data file 	Condes
WCD
	Macro token list 	WordPerfect for Win
WCH
	WordPerfect Macro Facility 	WP
WCM
	Data transmission file 	Microsoft Works
WCM
	Macro 	WordPerfect for Win
WCP
	Product information description 	WordPerfect for Win
WD
	InfoSelect Data file 	
WDB
	Database 	Microsoft Works
WDM
	Admin tool connection definition 	War FTP
WE?
	Packed mail 	FTN software
WEB
	WEB source code file 	Web Easy Professional
WebOOGL
	Web Object Oriented Graphics Library 	
WFB
	Turtle Beach WaveFront Bank 	AWAVE
WFD
	Turtle Beach WaveFront Drum 	AWAVE
WFM
	Form object 	dBASE Form Designer
WFN
	Font 	CorelDRAW
WFP
	Turtle Beach WaveFront Prog. 	AWAVE
WFT
	Web Family Tree 	GRAMPS
WFX
	Data file 	Winfax
WG1
	Worksheet 	Lotus 1-2-3/G
WG2
	Worksheet 	Lotus 1-2-3 for OS/2
WID
	Width table 	Ventura Publisher
WIM
	Windows Imaging Format 	ImageX
WIN
	Window file 	FoxPro - dBASE
WIREFRAME
	Data 	EMSE mesh
WIX
	Windows Installer XML 	WiX
WIZ
	Page wizard 	Microsoft Publisher
WK1
	Spreadsheet 	Lotus 1-2-3 version 2.x - Symphony 1.1+
WK3
	Spreadsheet 	Lotus 1-2-3 version 3.x
WK4
	Spreadsheet 	Lotus 1-2-3 version 3.4
WKB
	Document 	WordPerfect for Win
WKE
	Spreadsheet 	Lotus 1-2-3 educational version
WKI
	Spreadsheet format 	Lotus 123 2x
WKQ
	Spreadsheet 	Quattro
WKS
	Spreadsheet 	Lotus 1-2-3 version 1A - Symphony 1.0, Microsoft Works
WKS
	Workspace 	Xlisp
WKZ
	Spreadsheet format 	Dos Navigator
WLK
	Graphics 	Virtus Walkthrough
WLK
	Walk Through for any game 	many
WMA
	Windows Media Audio audio file
WMC
	Backup of startup files by Windows MathCad autoexec.wmc 	MathCad
WMC
	Macro file 	WordPerfect for Win
WMC
	Text file 	WordMARC
WMDB
	Windows Media Player database 	Windows Media Player
WMF
	Windows MetaFile vector graphics 	
WIMP
	Graphics (Windows Magic Icon Palette) 	
WMV
	Windows Media Video video file
WN
	Text 	NeXT WriteNow
WNF
	Corel Draw Font File 	CorelDraw
WOA
	Swap file 	Windows 3.x
WOC
	Organization 	Windows OrgChart
WOW
	Music (8 channels) 	Grave Mod Player
WP
	Word Perfect Format 	WP
WP5
	Document 	WordPerfect 5.x
WPD
	Document 	WordPerfect 6.0 - PFS:WindowWorks
WPD
	Windows printer driver (uninstallable) 	Windows
WPF
	Fax 	WorldPort
WPF
	Form 	WordPerfect
WPG
	WordPerfect Graphics vector graphics 	DrawPerfect
WPJ
	Watcom C/C++ IDE project 	IDE.EXE
WPK
	Macros 	WordPerfect for Win
WPL
	MediaRack Wave Playlist 	MediaRack
WPL
	Windows Media Playlist, for Windows Media Player
WPM
	Macros 	WordPerfect
WPS
	Text document 	Microsoft Works
WQ!
	Compressed spreadsheet 	Quattro Pro
WQ1
	Spreadsheet 	Quattro Pro
WR1
	Spreatsheet 	Symphony 1.1 - 1.2 - 2
WRD
	Template 	Charisma
WRI
	Write editor format 	Write - WinWord
WRK
	Spreadsheet 	Symphony 1.0
WRL
	VRML file 	
WRP
	Archive 	Amiga WARP
WRS
	Windows Resource eg. might indicate error if word cannot open 	WordPerfect for Win
WS
	APL Worksheet 	
WS
	Text file 	WordStar 5.0-6.0
WS2
	Text file 	WordStar 2000
WSD
	Document 	WordStar
WSP
	Workspace 	Fortran PowerStation
WSQ
	Wavelet-packet Scalar Quantization Format 	
WSRC
	X-wais source 	
WST
	Text file 	WordStar
WTR
	Working Timetable rules file 	Simsig
WTT
	Working Timetable timings file 	Simsig
WTF
	World of Warcraft Data File 	World of Warcraft
WTF
	WinTaper Data
WWB
	Button bar for document window 	WordPerfect for Win
WWK
	Keyboard layout 	WordPerfect for Win
WXH
	Program/Script File 	WaxHtml Web Programming Language
WXP
	Document 	EXP for Windows
[edit] X
Ext. 	Description 	Used by
X
	Archive 	X1.EXE
X
; 	AVS X image file 	SDSC Image Tool
X
	DirectX 3D object
X
	LEX source code file 	
X
	XBasic Source code file 	Xbasic
X3D
	x3d and xdart Formats 	
XA
	XA audio file 	used in SimCity 3000 by Maxis, also by Sony Playstation
XAR
	Xara file 	Project document used by vector graphics editor Xara Xtreme, previously known as Xara Studio. Early versions used the extension 'ART'.
XBE
	Xbox Executable 	Xbox
XBM
	X11 Bitmap graphics file 	
XCF
	Gimp image file 	The Gimp
XCK
	Extended crack file (usually text) 	
XCL
	Xtree for Windows Script file 	Xtree for Win
XDF
	OS/2 extended disk format image 	XDFCOPY.EXE
XDM
	Directory Manipulator for 32-bit Protected Mode 	Xenotech Research Labs
XE
	Xenon - for Associative 3D Modeling 	Ashlar-Vellum
XEX
	Xbox 360 Executable File
XFN
	Printer font 	Xerox 4045 - Ventura Publisher
XFR
	Ventura Publisher Bitmap Editor Font file 	
XFT
	24 pin printer font 	ChiWriter
XI
	Fast Tracker 2 instrument file 	AWAVE
XI
	Fastracker 2.0 Instrument File 	Fastracker 2.0
XIF
	Xerox Image Format 	Pagis Pro 2.0 and 3.0
XLA
	Add-in macro sheet 	Microsoft Excel
XLA
	XLib Archive 	xlibpas2.zip
XLB
	Microsoft Excel Toolbar 	Microsoft Excel
XLC
	Microsoft Excel Chart 	Microsoft Excel
XLD
	Microsoft Excel Dialog 	Microsoft Excel
XLK
	Microsoft Excel Archive 	Microsoft Excel
XLL
	Microsoft Excel Dynamic Link Library 	Microsoft Excel
XLM
	Microsoft Excel Macro File 	Microsoft Excel
XLS
	Microsoft Excel Spreadsheet 	Microsoft Excel
XLSB
	Microsoft Excel 2007 Binary Workbook (BIFF12)(Spreadsheets) 	Microsoft Excel 2007 (see Microsoft Office 2007 file extensions)
XLSX
	Office Open XML Workbook (Spreadsheets) 	Microsoft Excel 2007 (see Microsoft Office 2007 file extensions)
XLT
	Microsoft Excel Template 	Microsoft Excel
XLT
	Translation table 	Lotus 1-2-3 - Symphony - Procomm Plus
XLV
	Microsoft Excel Module 	Microsoft Excel
XLW
	Microsoft Excel Workbook 	Microsoft Excel
XM
	Fast Tracker 2 extended module 	AWAVE, Mod4Win, FastTracker, ImpulseTracker
XM
	Music format 	FastTracker - Cubic Player
XMOD
	Monarch Model 	Monarch Professional
XMI
	Compressed eXtended MIdi music 	
XML
	eXtensible Markup Language file
XMF
	eXtensible Music Format
XMPZ
	XML Miradi Project Zipfile 	Miradi
XMV
	video 	Xbox
XNF
	Standard Network File form 	
Xnn
	Secondary indexes 	Borland Paradox
XOF
	RenderMorphics 	
XP
	eXtended Pattern 	FastTracker 2.0
XPM
	X11 Pixel Map graphics file 	
XQT
	Executable file 	Waffle
XQT
	Macro sheet 	SuperCalc
XRF
	Cross-reference file 	
XSF
	data 	Microsoft InfoPath file
XSPF
	XML Sharable Playlist Format 	
XTB
	External translation table 	LocoScript
XTP
	XTreeGold overlay 	XTreeGold
XVF
	Xyngo Video File 	Xyngo Video Board
XWD
	X Window System window dump image graphics file 	SDSC Image Tool
XWK
	Keyboard mapping 	Crosstalk
XWP
	Session 	Crosstalk
XWP
	Text file 	Xerox Writer
XX
	Encoded file (ASCII) 	XXENCODE
XXE
	Encoded file (ASCII) 	XXENCODE
XY
	Text file 	XY Write
XY3
	Text file 	XYWrite III
XYW
	Text file 	XyWrite III
XYZ
	Molecular coordinates 	XMol, RasMol
[edit] Y
Ext. 	Description 	Used by
Y
	Archive (Amiga) 	Yabba
Y
	YACC grammar file 	Yacc/Bison
YAL
	Data custom/nature.yal 	Arts & Letters
YC
	Archive 	YACC (YAC.EXE)
Ynn
	Secondary index 	Borland Paradox
YMP
	Yast Meta Package 	YAST2 (SUSE Linux Package Manager)
YST
	Data 	YASRT Raytracer scene
YRD
	Yard Tracks File 	FYM
YUV
	Graphics format (YUV) 	
YY
	Bison grammar file 	Bison
YZ
	Archive 	YAC
[edit] Z
Ext. 	Description 	Used by
Z
	Archive 	WinZipNT - COMPRESS - PACK
Z01-Z99
	Split WinRAR Archive
Z3
	Infocom game module 	
Z3D
	Zmodeler-file 	Zmodeler 1 & 2
Z64
	Nintendo 64 ROM 	Project64 Nintendo 64 emulator
Z80
	Snapshot 	ZX Spectrum emulator by g.a.lunter
ZAD
	ZFax digitized voice file 	ZFax
ZDG
	Compressed ZiffNet text document 	Zview
ZED
	BitTorrent Link 	Podmailing
ZER
	Data file
ZIP
	Archive 	PKZip - WinZip - Mac OS X

