| ctp | CakePHP Template |
| ctrace | Android System Trace Data |
| ctrl | Oracle WebLogic Workshop Controls |
| cts | ABC Permanent Locations Data |
| ctsym | Visual Studio Command Table Symbols File |
| ctx | Visual Basic User Control Binary File |
| ctxt | BlueJ Context File |
| cu | CUDA Source Code |
| cuf | Turbo C Utilities Form Definition |
| cuh | CUDA Header |
| cuo | CUDA Object |
| curl | Curl Applet |
| cv | Microsoft CodeView Data |
| cv4 | Microsoft CodeView Graphics Data |
| cvb | Borland Database Engine Internationalization Data |
| cvip | NI LabWindows/CVI Profiler Data |
| cvsignore | CVS Ignore File |
| cvsrc | CVS Configuration Data |
| cweb | CWEB Source Code |
| cwlink | CodeWarrior Link Data |
| cwproj | C Omega Project |
| cwproj | Clarion 7 Project |
| cx | Codemapper Script |
| cxx | C++ Source Code |
| cy | Cycript Source Code |
| d | D Source Code |
| d | GCC Dependency File |
| d4 | Dataphor Source Code |
| d43 | IAR System MSP430 Debug Data |
| d4c | Dataphor Catalog Data |
| da | Gcov Compiled Output |
| da | Gcov Data File |
| dabriefcase | RemObjects Data Abstract File Briefcase |
| daconfig | RemObjects Data Abstract Configuration |
| daconnections | RemObjects Data Abstract Connections Data |
