| csj | BlackBerry Code Signing Data |
| csk | BlackBerry Code Signing Keys |
| cskin | CD Art Display Skin |
| csm | Mail.dat Container Summary File |
| csm | Chemical Style Markup Language Data |
| csml | Chemical Style Markup Language Data |
| csn | Race Studio 2 Custom Sensors Data |
| csom | Qualcomm Eudora for Mac Creator Code Data |
| cson | CoffeeScript Object Notation |
| csp | CHARTrunner Pareto Style |
| cspl | Mozilla Firefox CSPL Data |
| csplan | SPSS Sampling Plan |
| css | Scream Center for Seismic Studies Data |
| cssr | CSD Crystal Structure Search and Retrieval Data |
| csstore | iOS Cache Data |
| cssx | Now Platform External CSS |
| cst | ClearSilver Template File |
| cst | SAM Constraints Data |
| cst | CHARTrunner Control Chart Style |
| csup | Clan Short Roster Database |
| csutil | ColorSync Utility Data |
| csview | Chaoscope View Data |
| csvx | uProduce Server CSVX Data |
| csy | ACDSee Canvas Symbol Data |
| ct | Cheat Engine Cheat Table |
| ct | ETCBC Chapter Data |
| ct2 | C-Trend II Data |
| ct3 | Casio WK-1800 User Tones Data |
| ct4 | CaseMap 4 Template |
| ct4im | CrazyTalk Data |
