| Abbreviation | Definition |
|---|---|
| CK3 | Game data (iD/Apogee Commander Keen 3) |
| CK4 | iD/ Apogee Commander Keen 4 Game data |
| CK5 | Game data (iD/Apogee Commander Keen 5) |
| CK6 | Game data (iD/Apogee Commander Keen 6) |
| CKB | C++ Keyboard mapping file |
| CL | Common LISP language source code file |
| CLA | Clarion Source file |
| CLASS | Java bytecode (compiled class - application) |
| CLB | Clipbook template (Super NoteTab) |
| CLD | CA CLipper Debugger configuration file |
| CLD | Clipper debugger configuration file ( CA Clipper) |
| CLE | Chinese Linux Extensions |
| CLP | Clip art Bitmap graphics |
| CLP | Compiler responce file (CA Clipper) |
| CLP | Windows 3.x Clipboard file |
| CLR | 1st Reader Color binary screen image |
| CLR | Color definitions (Photostyler) |
| CLR | Color scheme (Boxer/2) |
| CLS | Class definition file |
| CLS | Visual Basic Class module |