| ccmp | STAR-CD v4 Results Data |
| ccmt | STAR-CD v4 Transient Data |
| ccp4 | Collaborative Computational Project Number 4 Format Data |
| ccr | ASTM Continuity of Care Record |
| ccrf | Saba Centra Recording Studio Recording |
| ccrz | Saba Centra Recording Studio Recording |
| ccs | TrialDirector Clip Script |
| ccu | CryptLoad Update Data |
| ccv | SAP Business Objects Crystal Vision Report |
| ccw | Crossword Compiler Crossword File |
| ccwsln | Connected Components Workbench Data |
| ccz | Client-Course Manager Customized Report Distribution Data |
| cd | STK City Database Main File |
| cdb | Sybase PowerDesigner Conceptual Data Model Backup |
| cdbcmsg | CIM Database CMSG Data |
| cdcom | Circuit Diagram Compiled Components File |
| cde | CADKEY Dynamic Extension |
| cded | Canadian Digital Elevation Data |
| cdf | Affymetrix Chip Description File |
| cdf | ANDI/netCDF Chromatography Data |
| cdf | ECMG Content Definition File |
| cdf | InstallShield Components Definition |
| cdf | MicroSim PCBoard Component Definition Data |
| cdf | Microsoft Channel Definition Format Data |
| cdf | netCDF Data |
| cdf-ms | ClickOnce Compiled Manifest |
| cdfx | Cindex Data |
| cdic | ConlangDictionary Data |
| cdj | DiscJuggler CD-Rom Data |
| cdl | Common Data Form Language File |
| cdlx | Adobe Audition CD Layout Data |
| cdm | Sybase PowerDesigner Conceptual Data Model |
| cdmia | Cloud Data Management Interface Capability Data |
| cdmic | Cloud Data Management Interface Container |
| cdmid | Cloud Data Management Interface Domain Data |