| ct | Cheat Engine Cheat Table |
| ct2 | C-Trend II Data |
| ct3 | Casio WK-1800 User Tones Data |
| ct4 | CaseMap 4 Template |
| ct4im | CrazyTalk Data |
| ct5 | CaseMap 5 Template |
| ct7 | CaseMap 7 Case Analysis Template |
| ct7model | CrazyTalk Model Data |
| ct7script | CrazyTalk Script |
| ct8 | CaseMap 8 Template |
| cta | ColorTouch Assistant Data |
| ctb | Cherrytree SQLite Database |
| ctbl | Xamine Data |
| ctd | Cherrytree XML Data |
| ctde | Sony Click to Disc Data |
| ctf | ECMG Content Transformation File |
| cth | MegaPOV Cloth Simulation Data |
| cti | Collectorz.com Template Info File |
| ctlg | elcoCAD Catalog Data |
| ctlx | myCatalogs Database |
| ctm | CrazyTalk Model Data |
| ctmdpi | MRMC Rate Matrix Data |
| ctn | CADTERNS Sloper |
| ctpx | Microvellum Cut Parts File |
| ctr | BrainVoyager QX Contrast Data |
| cts | CrazyTalk Script |
| cts | GodswMobile Contacts Transfer Backup |
| ctt | MSN Messenger Contact List |
| ctx | CyberTracker Exported Data |
| ctz | Cherrytree Password Protected Data |
| cu | CU-SeeMe Data |
| cu | my Knowledge Explorer Change Unit |
| cu1 | PhotoLine 4 Curve Data |
| cu3 | PhotoLine 4 Curve Data |
| cub | Gaussian Cube Data |