| cgt | SmartCAM Code Generation Template |
| cgx | Autodesk Land Desktop Label Style |
| ch10 | IRIG 106 Original Recording Data |
| ch5 | VisIt CH5 Data |
| ch6 | ZX-Paintbrush Character Data |
| ch8 | CHIP-8 Program |
| ch8 | ZX-Paintbrush Character Data |
| cha | Adobe Photoshop Channel Settings |
| changedb | SQLite Changes Data |
| char | Nintendo DS Character Tile Data |
| charset | Mac OS X Character Set Data |
| chatlog | Adium Chat Log |
| chb | CHMReader.NET Internal Data |
| chb | OLE DB Checkbook Data |
| chc | HCFR Colorimeter Data |
| chck | Microsoft Exchange Database Check Data |
| check | CASTEP Check Binary |
| chem | TI bqEASY Chemistry Data |
| chg | Quicken Online Data |
| chg | Windows Netlogon ChangeLog |
| chj | IBM SPSS Interview Cache |
| chk | DB/TextWorks Check Textbase Problem Report |
| chk | Epidata Defined Checks |
| chk | Gaussian Checkpoint File |
| chk | Saved File Fragment |
| chls | Charles Session Data |
| chlsj | Charles Proxy Recording Data |
| chml | Chameleon Studio Database |
| chn | Ethnograph Data |
| chn | MODTRAN CHN Output File |
| chp | Affymetrix Probe Array Results File |
| chq | Help Combined Full-text Search |
| chr | Altair FEKO FEST3D S-parameter Matrix Data |
| chr | Autodesk 3D Studio Max Character File |
| chs | MotionTracking Chromatic Shift Correction Data |