C

  .C    C Program File
        Check Point Site Configuration for Secure Remote
  .C??  Winace Compressed File
  .C00  Ventura Print File
  .C01  Typhoon Wave File
  .C2D  IsoBuster File
  .C86  C86 C Program 
  .C--  Sphinx C-- Source code
  .CA   Telnet Server Initial Cache Data File
        DATAIR FlexPlus Data File
  .CA7  Beta 44 Job File
  .CAB  Cabinet File (Microsoft installation archive)
  .CAC  dBase IV Executable File
  .CAD  Softdesk Drafix CAD File
  .CAF  Southern Company Terrestrial Data Acq
  .CAG  MS Clip Gallery Catalog File
  .CAL  SuperCalc Worksheet
        Calendar File
        Cals Raster File [SwiftView]
  .CAM  Casio Camera Graphic  [Viewer]
  .CAN  Navigator Fax
  .CAP  Ventura Caption
        Network Associates Sniffer Capture File
        Telix Session Capture
        Compressed Music File
  .CAR  AtHome Assistant File
  .CAS  Comma-delimited ASCII File
  .CAT  dBase Catalog
        Quicken IntelliCharge Categorization File
  .CB   MS Clean Boot File
  .CBC  CubiCalc Fuzzy Logic System File
  .CBI  IBM Mainframe Column Binary Formatted File
  .CBL  COBOL Program
  .CBM  XLib Compiled Bitmap
  .CBT  Computer Based Training
  .CC   C++ Program File
        Visual dBASE Custom Class File
  .CCA  CC:Mail File
  .CCB  Visual Basic Animated Button Configuration
  .CCC  Chat
        Curtain Call Native Bitmap Graphic
  .CCD  CloneCd Related File
  .CCE  Calendar Creator Plus Data File
  .CCF  OS/2 Multimedia Viewer Configuration File
        Symphony Communications Configuration File
  .CCH  Corel Chart
  .CCL  Intalk Communication Command Language
  .CCM  Lotus CC:Mail Mailbox
  .CCN  Vitalize! Game File  [Played via IE plug-in]
  .CCO  CyberChat Data File  
  .CCR  Chat Room Shortcut
  .CCS  CONKY CeZaR Stribas International
  .CCT  Macromedia Director Shockwave Cast
  .CD1  DATAIR Cafeteria Document System Data File
  .CD2  DATAIR Cafeteria Document System Custom Text File
  .CDA  CD Audio Track
  .CDB  Turbo C Database
        Clipboard File
        One Page from a ROM With a View Project File
        CardScan Database
        PowerDesigner Conceptual Model Backup File  
  .CDC  Chromeleon Driver Configuration Plugin
  .CDD  Chromeleon Device Driver
  .CDF  Comma Delimited Format
        Cyberspace Description Format
        MS Channel Definition Format
        InstallShield Components Definition File
        NetCDF Graphic File
  .CDI  Phillips Compact Disk Interactive Format
  .CDK  Atari Calamus Document
  .CDM  PowerDesigner Conceptual Model File  
        Visual dBASE Custom Data Module
  .CDR  Corel Vector Graphic
        Raw Audio-CD Data
  .CDT  Corel Draw Template
  .CDX  Compound Index
        Corel Draw Compressed Drawing
        MS Visual Foxpro Index
        Active Server Document
        Microstation Cell Library Index
  .CDZ  ROM With a View Project File
  .CE   FarSide Computer Calendar File
  .CEG  Continuous Edge Graphic
        Tempra Show Bitmap Graphic
  .CEL  Autodesk Animator Graphic
        CIMFast Event Language File
        Kiss Paper Doll File
        Microstation Cell Library
  .CER  Certificate File  
  .CEX  The Currency Exchanger Rate File
        INMOS Transputer Development System Occam User Program
  .CF   Imake Configurtion File
  .CFB  Comptons Multimedia File
  .CFF  Capabilities File for FOUNDATION(tm) Fieldbus H1 (31.25 kbit/s)
  .CFG  Configuration (various)
  .CFH  Capabilities File for FOUNDATION(tm) Fieldbus HSE (100 Mbit/s)
  .CFL  Corel Flowchart File
  .CFM  Corel FontMaster
        Cold Fusion Template File
        Visual dBASE Windows Customer Form
  .CFN  Atari Calamus Font Data File
  .CFO  TCU Turbo C Utilities C Form Object
  .CFP  Complete Fax Portable Fax File
  .CGA  Ventura CGA Screen Characters
  .CGI  Common Gateway Interface Script
  .CGM  Computer Graphics Metafile
  .CGP  NetCaptor CaptorGroup
  .CH   Clipper Header
        OS/2 Configuration File
  .CH3  Harvard Chart (Harvard Graphics taken over by Serif)
  .CH4  Charisma 4.0 Presentation
  .CHA  Adobe Pagemaker Kerning Data
  .CHD  FontChameleon Font Descriptor
  .CHF  pcAnywhere Remote Control File
  .CHI  Chiwriter Document
  .CHJ  Help Composer Project
  .CHK  CHKDSK/SCANDISK Output
        WordPerfect Temp File
  .CHL  Chromeleon Channel Raw Data
        Configuration History Log
  .CHM  Compiled HTML Help
  .CHN  Ethnograph Data File
  .CHP  Ventura Publisher Chapter
  .CHR  Character or Font File
  .CHT  Cheat Machine Data File
        ChartViewer dBase Interface File
        Harvard Graphics Vector File (Harvard Graphics taken over by Serif)
  .CIF  Ventura Chapter Information
        CalTech Intermediate Graphic
        Easy CD Creator Image
        pcAnywhere Caller File
        Ventura Converted Image File
        Colombo Ipermedia File
  .CIL  Clip Gallery Download Package
  .CIM  Sim City 200 File
        CIMEX Cimpack Design Drawing File
  .CIN  OS/2 Change Control File
  .CIR  SuperMax E-CAD Save-File Command
  .CIT  Intergraph Scanned Image
  .CIX  TCU Turbo C Utilities Database Index
  .CK1  iD/Apogee Commander Keen 1 Data File (.CK1 to .CK6)
  .CKB  Borland C++ Keyboard Mapping File
  .CKP  Ingres Checkpoint File
  .CL   Generic LISP Source Code
  .CL3  Easy CD Creator Layout File
  .CL4  Easy CD Creator Layout File
  .CLA  Java Class File (usually .CLASS but can be shortened)
  .CLG  Disk Catalog Database
  .CLK  Corel R.A.V.E. Animation File
  .CLL  Crick Software Clicker File  
  .CLO  Cloe Image
  .CLP  Windows Clipboard/Picture  [Viewer]
        Quattro Pro Clip Art
        Clipper 5 Compiler Script
  .CLR  WinEdit Colorization Word List
        1st Reader Binary Color Screen Image
        PhotStyler Color Defintion
  .CLS  Visual Basic Class Module
        C++ Class Definition
  .CLW  Microsoft Visual C++ Class Wizard File
  .CM   Craftman Data File
  .CM4  ClipMate Data File
  .CMA  Applix TM1 Database File (text)
  .CMB  Chromeleon Backup Archive
  .CMD  OS/2, WinNT Command File
        DOS CP/M Command File
        dBase II Program File
        1st Reader External Command Menu
  .CMF  Creative Music File
        Corel Metafile
  .CMG  Chessmaster Saved Game
  .CMK  Card Shop Plus File
  .CML  Cheat Machine Library File (Windows)
        PADGen Company Info File
  .CMM  CEnvi (ScriptEase:Desktop) Batch File
  .CMP  Leadview Bitmap
        Open Access File
        Address Document
        JPEG Bitmap
        CorelDRAW Postscript Printer Header
        Route 66 Address Document
        MS Word for DOS User Dictionary
  .CMR  MediaPlayer Movie
  .CMU  Carnegie Mellon Univeristy Stereo Raster Image
  .CMV  Corel Move Animation
  .CMX  Corel PhotoPaint Image
        Corel Presentation Exchange Image
        Apple Viewer File
  .CNC  CNC General Program Data
  .CNF  Configuration (various)
        SpeedDial
  .CNM  Windows Application Menu Options and Setup File
  .CNQ  Compuworks Design Shop File
  .CNT  Help File Contents (and other contents needs)
  .CNV  MS Word Data Conversion File
        WS_FTP Pro Upload Conversion File Data
        WordPerfect Temporary File
  .COB  COBOL Program File
        Caligari Truespace Format
        TrueSpace2 Object
  .COD  Code List
        Compiler Program Code
  .COD  Multiplan Data File
        dBase Template Source File

        FORTRAN Compiled Code
        Video Text File
  .COL  Autodesk Color Palette
        Multiplan Spreadsheet
        Lotus Notes Import Column Description File
  .COM  Command (Executable file)
  .CON  Knowledgeware Consolidation File
        Tree Professional Conifer Creator File
        Simdir Configuration File
  .COP  Tree Professional Conifer Creator Image File
  .CP8  CP8 256 Gray Scale Image
  .CPD  Fax Coversheet
        Corel PrintOffice File
        Complaints Desk Script
  .CPE  Fax Coversheet
  .CPF  Complete Fax File
  .CPG  3dize® Cool Page File
  .CPH  Corel Print House Image
  .CPI  Code Page Information
        ColorLab Image
  .CPJ  CeQuadrant CD Project
  .CPL  Control Panel Extension
        Corel Color Palette
        Compel Presentation
  .CPO  Corel Print House File
  .CPP  C++ Program
        CA-Cricket Presents Presentation
  .CPR  Corel Presents Presentation
        Knowledge Access Graphics
        INMOS Transputer Development System Occam Program Code Fold
  .CPS  Antivirus Checksum File
        Central Point PC Tools Backup
        Colored PostScript File
  .CPT  Macintosh Compressed File
        Corel Photo-Paint Image  [Viewer]
        dBase Encrypted Memo
        CA Cricket Presents Template
  .CPX  Control Panel Applet
        CryptaPix Encrypted Image
        Corel Presentation Exchange Compressed Drawing
  .CPY  Copy Books Data File
  .CPZ  COMPOZ Music Text

  .CRD  Cardfile (Windows 3.x Database)
  .CRF  Zortech C++ Cross-Reference File
  .CRH  MS Golf Image File
        Links Games Course File
  .CRL  Certificate Revocation List
  .CRP  dBase Encrypted Database
        Visual dBASE Custom Report
        Corel Presents Run-Time Presentation
  .CRS  WordPerfect 5.1 for Windows File Conversion Resource
        Links Games Course File
  .CRT  Certificate File
        Oracle Terminal Settings Info
        UNIX Crontab File (not a required extension for Crontab)
  .CRU  CRUSH Compressed Archive
  .CRX  Links Games Course File
  .CRY  Crypto Chat II Encrypted Notebook-content
  .CRZ  Links Games Course File
  .CS   C#.NET Source File
  .CSA  Comma Deliminated Text
  .CSC  Corel Script
  .CSD  Bitstream Fontware File
        Chemsoft® MSDS Database File
  .CSG  Statistica Graph File
  .CSH  Hamilton Labs C Shell Script File
  .CSI  Cyberautograph Signed Item
  .CSK  Claris Works
  .CSM  Borland C++ Symbol File
        Borland C++ 4.5 Precompiled Header
        Kodak DC265 Camera Script

  .CSP  PC Emcee On-Screen Image
  .CSQ  Foxpro Queries
  .CSS  Hypertext Cascading Style Sheet
        Stats+ Datafile
        Statistica Datasheet
  .CST  Macromedia Director Cast File
  .CSV  Comma-Separated Variables
        CompuShow Adjusted EGA/VGA Palette
  .CT   Scitex CT Bitmap
  .CTC  PC Installer Control
  .CTF  TIFF Compressed File
        Symphony Character Code Translation
  .CTL  Setup Information (various)
        User Control (various)
  .CTX  Compressed Text
        Visual Basic User Control Binary File
        Pretty Good Privacy (PGP) Ciphertext File
        MS Online Course Text
  .CTY  SimCity City File
  .CUE  MS Cue Cards Data
        Description File for a CD-Image [Fireburner.com or Goldenhawk.com]
  .CUF  Turbo C Utilities Form Definition
  .CUL  IconForge/ImageForge Cursor Library
  .CUR  Cursor  [Viewer]
  .CUT  Dr. Halo Bitmap Graphic
        INMOS Transputer Development System Occam Utility Package
  .CV   Corel Versions Archive
        MS CodeView Information
  .CV4  Codeview Colors
  .CVG  Image File
  .CVP  WinFax Cover Page
  .CVS  Canvas Drawing File
  .CVT  dBase Converted Database
  .CVW  Codeview Colors
  .CWE  Crossword Express
  .CWK  Claris Works Data also see AppleWorks
  .CWS  Claris Works Template also see AppleWorks
  .CXT  Macromedia Director Protected Cast File
  .CXX  Zortech C++ Program
  .CYN  Cynex Root55 Program Extension
  .CYP  Cypherus Encrypted Archive