| coo | Tajima Embroidery Data File |
| cookie | HTTP Cookie Data |
| cool | QB - Text Analyzer Vocabulary Data |
| coords | Ribbons Coords Data |
| cor | CYANA DG Cartesian Coordinate File |
| costyle | Capture One Style Data |
| cov | RFM Covariate Table |
| covsym | Gumshoe Coverage Symbols Data |
| cow | Cowsay Data |
| coz | EFILive Calibration Data |
| co_ | Compressed COM File |
| cp1 | CARE-S InfoWorks Phosphorus Detail Data |
| cp4 | Adobe Captivate 4.0 Simulation Data |
| cpa | Cadstar PCB Design |
| cpaa | Adobe Captivate Shared Action Data |
| cpd | Adobe RoboHelp Cache Project Database |
| cpd | SmartWare Compiled Printer Descriptor |
| cpg | CATS PG File |
| cpglog | Motorola Codeplug Session Log |
| cpi | Lifo-Pro Consumer Price Index |
| cpi | MS-DOS Code Page Information |
| cpixml | iTWO Construction Process Integration XML |
| cpl | TINA Complex Parameter List |
| cpl | Tekla Structures Contour Plate Properties |
| cprr | Adobe Captivate XML Recording Script |
| cpt | Ccrypt Encrypted File |
| cpt | Mail.dat Component File |
| cpt | Casio WK-1800 Pattern Sequerncer Pattern |
| cpt2 | M-Tron Pro Library |
| cptl | Adobe Captivate 5 Template |
