| cub | ISIS 2 Cube |
| cube | Gaussian Cube Data |
| cud | ChmUpDate Data |
| cuix | Autodesk AutoCAD Custom User Interface |
| cul | Windows Cursor Library |
| cup | Naviter SeeYou Waypoint Data |
| cur | Oasys T/HIS Curve File |
| cursorfx | CursorFX Theme |
| curv | Genetica Mathematical Curve |
| curve | ANSYS TurboGrid Curve File |
| curxptheme | CursorXP Theme |
| cus | WindLDR Custom Monitor Data |
| cus | Autodesk AutoCAD Custom Dictionary |
| cuts | TS-Doctor Cuts Data |
| cuw | Toyota Calibration Update Wizard Data |
| cva | ACDSee Canvas Sequence Set |
| cvd | ClamAV Virus Database |
| cvd | Bitdefender Antivirus Database |
| cvf | CPU-Z Validation |
| cvj | Cabinet Vision Solid Job |
| cvj | Corticon Vocabulary Data |
| cvl | ARGUS Valuation-Capitalisation Export File |
| cvn | CineVision Encoding Session Data |
| cvz | Card Vault Inventory Data |
| cw5 | CodeWallet Pro 5 Wallet |
| cw6 | COMPRESS Vessel Model File |
| cwa | Castelware Inventory Audit Data |
| cwdb | ClarisWorks Database |
| cwie | CodeWarrior Module Data |
| cwm | Common Warehouse Metamodel File |
| cwr | WrapCandy Template |
| cww | Crossword Weaver Puzzle |
| cwx | CodeWallet Pro 5 Form |
| cxa | ANSYS Fluent Solution Animation File |
| cxb | Custody X Change CXB Data |