| CCP
| Key definition for CP/M Plus
| [[CP/M 3.0|CP/M 3.0]]
|-
| COM
| Executable CP/M or [[SymbOS|SymbOS]]-SymShell program
| [[CP/M|CP/M]], [[SymShell|SymShell]]
|-
| CUT
| [[AMX Pagemaker|AMX Pagemaker]]
|-
| DD *
| Device driver for GSX (CP/M Plus)
| [[CP/M 3.0|CP/M 3.0]]
|-
| DEU
| SUB
| Submit/Batch file (CP/M)
| [[CP/M|CP/M]]
|-
| SYS
| GSX file (CP/M)
| [[CP/M|CP/M]]
|-
| TXT