| cas | Comma-Delimited ASCII File |
| case | SlipCover Case Template |
| catdrawing | Catia Drawing |
| catpart | Catia V5 Part Description Document |
| catproduct | Catia V5 Product Description Document |
| catprt | Catia V5 Part Description Document |
| cax | VCollab Pro 3D Model |
| cbcx | Comic Book Creator Document |
| cbt | Computer-based Training Document |
| cbtx | Comic Book Creator Template |
| cbw | ComicRack WebComic Document |
| cc5 | Calendar Creator v5 Document |
| cce | Calendar Creator v2 Document |
| ccitt | CCITT Group 3 and Group 4 Encoded Fax |
| cct | Adobe Director Compressed Cast |
| ccz | DxDesigner Compressed PCB Layout |
| cd2 | Click'n Design 3D Document |
| cdb | Pocket Access Document |
| cdc | Nero Cover Designer Import Document |
| cdd | ConceptDraw Pro Drawing |
| cddx | Circuit Diagram Document |
| cddz | ConceptDraw PRO v10 Document |
| cdk | CADKEY Document |
| cdl | CADKEY CAD Advanced Design Language File |
| cdml | Creately Document Markup Language Document |
| cdmm | ConceptDraw MINDMAP Document |
| cdmt | ConceptDraw MINDMAP Template |
| cdmz | Compressed ConceptDraw MINDMAP Document |
| cdn | Click'n Design 3D CD Label Document |
| cdo | Crescendo Music Notation |
| cdpx | ConceptDraw PROJECT XML Document |
| cdpz | ConceptDraw PROJECT Document |
| cds | ChemDraw Stationery Document |
| cdsg | DrawMusic Chord Song |
| cdsx | ConceptDraw PROJECT XML SlideShow File |