Dynamic Chiropractic – September 7, 1998, Vol. 16, Issue 19

File Formats and Extensions

By Michael Devitt
Most computer users are familiar with file extensions, those alphanumeric characters that follow the file name and dot (e.g., "filename.txt"). If you've ever saved a word processing document or downloaded a picture from the Internet, you've probably noticed those extensions.
While they may not seem important, extensions do help describe the contents of a file and making them compatible with other programs.

The file name extension serves several purposes. It allows a file's format to be described as a part of its name, so that users can quickly identify a particular type of file without having to open or use it. The extension also helps other applications, such as word processing programs and image editors, recognize whether the file being used is one that the application can work with.

In the file named ("chiropractic.doc"), the "doc" extension tells the user that the file is a Microsoft Word document without the user having to open the file and see what it is. It also lets the Microsoft Word application know that it is a file the program can open.

Some operating systems limit file extensions to only three characters. One nice feature of the Macintosh operating system is that it does not have a limit to its file extension system. This explains why some web pages have only a .htm extension, while others end with .html.

File Formats from A to Z

There are literally hundreds of file formats and extensions, and the list continues to grow. To help users identify what certain extensions mean, we've come up with this compendium of file name extensions that indicate the format or use of a file and a brief description of that format.

Extension Description
ABKCorel Draw AutoBackup
ACLCorel Draw 6 keyboard accelerator
ACMUsed by Windows in the system directory
ACPMicrosoft Office Assistant Preview file
ACTMicrosoft Office Assistant Actor file
ACVOS/2 drivers that compress and decompress data
ADAfter Dark screen saver
ADBAppointment database used by HP 100LX organizer
ADDOS/2 adapter drivers used in the boot process
ADM After Dark MultiModule screen saver
ADPUsed by FaxWorks for fax modem interaction
ADRAfter Dark Randomizer screen saver
AF2, AF3ABC Flowchart file
AFMAdobe font metrics
AIAdobe Illustrator drawing
AIFApple Mac AIFF sound
ALBJASC Image Commander album
ALL, YALArts & Letters files
ANCCanon Computer Pattern Maker file that is a selectable list of pattern colors
ANIAnimated cursor
APIApplication Program Interface file
APRLotus Approach 97 file
APSMicrosoft Visual C++ file
ARCLH ARC (old version) compressed archive
ARJRobert Jung ARJ compressed archive
ARTXara Studio drawing (or) Canon Crayola art file
ASAMicrosoft Visual InterDev file
ASCASCII (a basic text file)
ASDWinWord AutoSave
ASMAssembler language source file
ASPActive Server Page (an HTML file with a Microsoft server processed script)
ASPProcomm Plus setup and connection script
ASTClaris Works "assistant" file
ATTAT&T Group 4 bitmap
AVIMicrosoft Video for Windows movie
AWDFaxView document
B4, LPDHelix Nuts and Bolts file
BAKBackup file
BATBatch file
BFCWindows 95 Briefcase document
BI, BINBinary file
BIFGroupWise initialization file
BK, BK$Sometimes used to denote backup versions
BKSIBM BookManager Read bookshelf
BMPWindows or OS/2 bitmap
BRXA file for browsing an index of multimedia options
BTMBatch file used by Norton Utilities
CABMicrosoft cabinet file (program files compressed for software distribution)
CALCALS compressed bitmap (or) Calendar schedule data
CASComma delimited ASCII file
CATIntelliCharge categorization file used by Quicken
CBMicrosoft clean boot file
CCBVisual basic animated button configuration
CCFMultimedia viewer configuration file used in OS/2
CCHCorel Chart
CCMLotus CC:Mail "box" (for example, inbox.ccm)
CDACD audio track
CDFMicrosoft Channel Definition Format file
CDIPhillips Compact Disk Interactive format
CDR, CDT, CDXCorel Draw files
CELCIMFast Event Language file
CFBCompton's Multimedia file
CFGConfiguration file
CGICommon gateway interface script file
CGMComputer graphics metafile
CHOS/2 configuration file
CHKFile fragments saved by Windows Disk Defragmenter or ScanDisk
CHPVentura Publisher chapter
CHTChartViewer file (or) Harvard Graphics vector file
CILClip Gallery download package
CINOS/2 change control file that tracks changes to an INI file
CLASSJava class
CLPWindows Clipboard file
CLSVisual basic class module
CMDCommand file for Windows NT (or) DOS CP/M command file (or) dBase II program file
CMFCorel Metafile
CMPJPEG bitmap (or) Address document
CMVCorel Move animation
CMXCorel Presentation Exchange image
CNFConfiguration file used by Telnet, Windows, and other applications with varying internal formats
CNMWindows application menu options and setup file
CNQCompuworks Design Shop file
CNTWindows (or other) system content files
COBTrueSpace2 object
CODMicrosoft C compiler output
COMCommand file (program)
CPD, CPEFax Cover document
CPIMicrosoft MS DOS code page information file
CPLControl Panel extension (or) Corel color palette
CPPC++ code
CPRCorel Presents presentation
CPTCorel Photo Paint image
CPXCorel Presentation Exchange compressed drawing
CRDCardfile file
CRPCorel Presents run time presentation
CRTCertificate file
CSCCorel Script
CSPPC Emcee on screen image
CSVComma separated values file
CTScitex CT bitmap
CTLUsed in general to mean a file containing control information
CUEMicrosoft Cue Cards data
CURWindows cursor
CUTDr. Halo bitmap
CVCorel Versions archive (or) Microsoft CodeView information screen
CWK, CWSClaris Works data files
CXXC++ source code file
DATData file (or) WordPerfect merge data
DBFAston Tate dBASE database
DBXDataBeam image
DCRShockwave file
DCSDesktop Color Separation file
DCXFax image (based on PCX)
DEFSmartWare II data file (or) C++ definition
DERCertificate file
DIBDevice Independent Bitmap
DIFData Interchange Format spreadsheet
DIRMacromedia Director file
DIZDescription file
DLLDynamic Link Library
DOCFrameMaker or FrameBuilder document (or) WordStar document (or) Microsoft Word document
DOTMicrosoft Word document template
DPRBorland Delphi project header file
DRWMicrografx Designer/Draw
DSP, DSW,Microsoft Developer Studio files
DSQCorel QUERY file
DTFSymantec Q&A relational database file
DXFAutoDesk Drawing Interchange format
EMFEnhanced Windows Metafile
ENCEncore file
EPSEncapsulated PostScript image
EVYEnvoy document
EWLMicrosoft Encarta document
EXEExecutable file (program)
F, F77, FORFortran file
FARFarandole Composer music module file
FAVMicrosoft Outlook navigation bar
FAXFAX Type image
FH3Aldus Freehand 3 drawing
FIFFractal image file
FITSCCD camera image
FLC, FLIAutoDesk FLIC animation
FLTCorel filter
FMBOracle binary source code for form, version 4.0 and later
FMTOracle text format of form, version 4.0 and later (or) Microsoft Schedule+ print file
FMXOracle executable form, version 4.0 and later
FOGFontographer font
FONSystem font
FOTFont related file
FP, FP3FileMaker Pro file
FPXFlashPix bitmap
FRMFramkeMaker or FrameBuilder document (or) Form (or) Visual Basic form (or) Wordperfect merge form
FRXVisual Basic form stash file
GALCorel Multimedia Manager album
GCPGround Control Point files
GEDGraphic Environment Document (drawing)
GEMGEM metafile
GENVentura generated text file
GFCPatton & Patton flowchart file
GFI, GFX,Genigraphics Graphics Link presentation
GIDWindows 95 global index file
GIFCompuServe bitmap
GRA Microsoft graph
GRDGrid file
GRPProgram Manager Group
GZUnix G-zip compressed file
HC program header
HEDHighEdit document
HEX, HQXMacintosh BinHex files
HGLHP Graphics Language drawing
HLPHelp file
HPJVisual Basic Help Project
HPPC++ program header
HSTHistory file
HTM, HTMLHypertext document
HTXExtended HTML template
ICACitrix file
ICB, TGA,Targa bitmap
ICMImage Color Matching profile file
ICOWindows icon
IDDMIDI instrument definition
IDQInternet Data Query file
IDXSymantec relational database index file
IGFInset Systems metafile
IIFQuickBooks for Windows interchange file
IMAWinImage file
IMGGEM image
INCAssembler language or Active Server include file
INFInformation file
INIInitialization file
INPOracle source code for version 3.0 and earlier
INSInstallShield install script (or) X Internet sign up file
ISOLists the files on a CD ROM
ISPX Internet sign up file
ISUInstallShield uninstall script
IWIdlewild screensaver
JARJava Archive file (a compressed file for applets and related files)
JAVAJava source code
JBFPaint Shop Pro image browser file
JFF, JIF,JPEG image file
JMPSAS JMP Discovery chart to stats file
JSJavaScript source code
KDCKodak Photo Enhancer
KFXKoFax Group 4 image
LBMDeluxe Paint bitmap
LDBMicrosoft Access lock file
LEGLegacy document
LHA, LZHLH ARC compresed archive
LIBLibrary file
LISOutput file produced by a Structured Query Reporting (SQR) program
LOGLog file
LRCIntel Video Phone file
LSTList file
LWOLightwave Object file
LWPLotus WordPro 96/97 file
LZSSkyroads data file
M3DCorel Motion 3D animation
MACMacPaint image
MAD, MAF,Microsoft Access files
MAKVisual Basic or MS Visual C++ Project
MAPMap file
MASLotus Freelance Smartmaster file
MAXPaperport file
MAZHover maze data
MCCDialer10 calling card
MCSMathCAD image
MCWMicrosoft Word for Macintosh document
MERFormat for interchanging spreadsheet/database data; recognized by Filemaker, Excel, and others
METPresentation Manager metafile
MICMicrosoft Image Composer file
MMFMicrosoft Mail file
MMMMicrosoft multimedia movie
MODFastTracker, StarTrekker, Noise Tracker (etc.) music module file
MOVQuickTime for Windows movie
MP3MPEG Audio Layer 3 (AC3) file
MPE, MPEG,MPEG animation
MPPMicrosoft Project file (or) CAD file format
MSGMicrosoft Mail message
MSNMicrosoft Network document
MSPMicrosoft Paint bitmap
MUSMusic file
MVBMicrosoft Multimedia Viewer file
MWPLotus Wordpro 97 Smartmaster file
NAPNAP Metafile (vector image)
NSF, NTFLotus Notes files
OBD, OBZMicrosoft Office Binder file
OBJObject file
OCXMicrosoft Object Linking and Embedding custom control
OFNMicrosoft Office FileNew file
OFTMicrosoft Outlook template
OLB, OLEOLE Object files
ORG, OR2, OR3Lotus Organizer file
P10Tektronix Plot 10 drawing
PABMicrosoft personal address book
PALWindows color palette
PATCorel Draw pattern
PBKMicrosoft Phonebook
PBMPortable Bitmap
PCDKodak Photo CD image
PCLHP Laserjet bitmap
PCSPICS animation
PCTMacintosh PICT drawing
PCXZSoft PC Paintbrush bitmap
PDFAdobe Acrobat Portable Document Format (or) Netware Printer Definition File
PFA, PFBType 1 font file
PFCPF component
PFMPrinter font metrics
PGLHP Plotter drawing
PGMPortable graymap (bitmap)
PICPC Paint bitmap (or) Lotus picture (or) Macintosh PICT drawing
PIFProgram information file (or) IBM PIF drawing
PIXInset Systems bitmap
PJMKS source integrity file
PKGMicrosoft Developer Studio application extension
PLPerl program
PLTHPGL Plotter drawing (or) AutoCAD Plot drawing
PM5, PM6, P65Pagemaker 5.0-6.5 files
PNGPortable Network Graphics bitmap
PNTMacPaint graphic file
POT, PPA,Microsoft PowerPoint files
PP4Picture Publisher 4 bitmap
PPMPortable pixelmap bitmap
PRELotus Freelance presentation
PRFWindows system file
PRNPrint table (space delimited text)
PRSHarvard Graphics for Windows presentation
PRZLotus Freelance Graphics 97 file
PSPostscript interpreted drawing
PSDAdobe Photoshop bitmap
PSTMicrosoft Outlook personal folder file
PUBVentura Publisher publication (or) Microsoft Publisher document
QADPF QuickArt document
QBWQuickBooks for Windows file
QLBQuick Library
QRYMicrosoft Query
QT, QTMQuickTime Movie
QXDQuark XPress file
RPegasus Mail resource file
RA, RAMReal Audio sound
RASSun Raster Images bitmap
RAWRaw File Format (bitmap)
REGRegistration file
RLERun length encoded bitmap
RMReal Audio video file
ROVRescue Rover data file
RTFRich Text Format document
SAMAmi Professional document
SAVSaved game file
SCCMicrosoft Source Safe file
SCD, SCH, SC2Microsoft Schedule+ file
SCPDial Up Networking Script
SCRWindows screen saver (or) fax image
SCTScitex CT bitmap
SDL, SDR, SDTSmartDraw files
SEASelf expanding archive
SEPTagged Image File Format (TIFF) bitmap
SHBCorel Show presentation (or) document shortcut file
SHGHotspot bitmap
SHSShell scrap file
SHWCorel Show presentation
SITStuffit archive of Mac files
SLKSymbolic Link (SYLK) spreadsheet
SNDNext sound (or) Mac sound resource
SQCStructured Query Language (SQR) file
STYVentura Publisher style sheet
SVXAmiga 8SVX sound
SYSSystem file
TARTape Archive
TAZ, TGZUnix Gzip/Tape Archive
TEXTexture file
THEMEWindows 95 desktop theme
THNGraphics Workshop for Windows thumbnail
TIF, TIFFTag Image File Format (TIFF) bitmap
TLBOLE type library
TMPWindows temporary file
TRMTerminal file
TRNMKS Source Integrity project usage log
TTFTrueType font
TWFTabWorks file
TXTText file
UDFWindows NT Uniqueness Database file
URLInternet shortcut
USEMKS source integrity file
VBP, VBXVisual Basic files
VBWMicrosoft Visual Basic workspace
VIVirtual instrument file
VLBCorel Ventura library
VOCCreative Labs Sound Blaster sound file
VPVentura Publisher publication
VSD, VSWVisio Workspace file
VXDMicrosoft Windows virtual device driver
WAVWindows Waveform sound
WB1, WB2QuattroPro for Windows spreadsheet
WBKMicrosoft Word backup
WBLArgo WebLoad II upload file
WCMWordPerfect macro
WDBMicrosoft Works database
WEBCorelXara Web document
WIDVentura width table
WILWinImage file
WIZMicrosoft Word wizard
WK1, WK3, WK4Lotus 123 spreadsheet files
WKS Lotus 123 Worksheet spreadsheet (or) Microsoft Works document
WLLMicrosoft Word Add In
WMFWindows Metafile
WP, WPD, WordPerfect document
WP4, WP5, WP6  
WPGWordPerfect graphic
WPSMicrosoft Works document
WPTWordPerfect template
WPWNovel PerfectWorks document
WQ1, WQ2QuattroPro/DOS spreadsheet
WRIWrite document
WRLVirtual Reality model
WS1, WS2,WordStar for Windows document
WS3, WS4, WS5,  
WS6, WS7  
WSDWordStar 2000 document
WVLWavelet compressed bitmap
XARCorel Xara drawing
XLA, XLB,Microsoft Excel related files
XMFastTracker 2, Digital Tracker music module file
XTPXTree data file
XY3, XY4,XYWrite documents
YBKMicrosoft Encarta yearbook
ZUnix Gzip compressed file
ZIPZip file compressed archive
000 999Used to number backup versions of files; also used to number data files for multiple users of a small scale PC application
12M, 123Lotus 123 files
2GR, 3GRVGA graphics driver/configuration files
386A file used in an 80386 or higher microprocessor
#01 and higherA method of numbering picture files for film that has been scanned onto a PC
$$$Used by OS/2 to track archived files

As always, we welcome your comments. If you have any questions about the file formats mentioned above, feel free to contact me at the e-mail address listed below.

Michael Devitt
Huntington Beach, California
Tel: (714) 960-6577
Fax: (714) 536-1482


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