| cao | CAO Cryptographic Language Data |
| cap | Libpcap Captured Packets |
| caps | CaptureSaver Knowledge Base |
| capt | Linrock Capito Data |
| car | PC 1000 Calculation Result Data |
| caro | Adobe Acrobat Creator Code |
| cascii | CACTVS Chemical ASCII Format Data |
| castep | CASTEP Data |
| cat | Quicken IntelliCharge Categorization |
| cat | TINA Pro Catalog |
| cat4d | Maxon Cinema 4D Catalog |
| catalog | Catia Catalog |
| catfct | CATIA CATfct Data |
| catnls | CATIA NLS Data |
| catom | Chief Architect Catalogue Data |
| catraster | CATIA Raster Data |
| catshape | CATIA Shape Data |
| catswl | CATIA CATswl Data |
| catsystem | CATIA Functional Systems Data |
| cav | Kintraks Database |
| caw | SSIS Cache Data |
| cawr | Espresso Workreport Document |
| cb1 | CARE-S InfoWorks Biochemical Oxygen Detail Data |
| cb3 | CliBench Mk III Data |
| cb4 | Actuate Analytics Cube Data |
| cb5 | CubeAnimator LED Data |
| cba | DB/TextWorks SQL Textbase Definition |
| cbb | DB/TextWorks SQL Textbase Structure Definition |
| cbc | MODFLOW Cell-by-cell Flow Data |
| cbcp | CodeBaby Production Studio Character Package |
| cbg | CyberGauge Data File |
| cbin | CACTVS Binary File |
| cbk | DYMO CardScan Backup Data |
| cbml | Vernier Logger Pro Data |
| cbmv | Comic Book Millennium Collection Data |