| cyi | Clustify Input File |
| cyp | FCB Cypher Document |
| czd | CAD Zone Drawing |
| d2d | 3D Fassade Plus CAD Document |
| dae | Collada Digital Asset Exchange |
| dap | Microsoft Access Data Access Page |
| dc | DesignCAD Document |
| dc1 | DevCad Document |
| dc2 | DevCad CAM Pro Document |
| dc2 | DesignCAD 2D Document |
| dc3 | DesignCAD 3D Document |
| dc5 | DynaCAD v5 Document |
| dc6 | DynaCAD v6 Document |
| dca | IBM DisplayWrite Document |
| dch | DipTrace Schematic Document |
| dcw | DynaCAD v4 Document |
| dcz | DynaCAD Document |
| ddf | Alpha Journal Pro Document |
| ddf | My Personal Diary Document |
| ddif | DIGITAL Document Interchange Format |
| ddrw | ClarisDraw Drawing |
| de | DrawExpress Diagram Document |
| dec | DEC DX Document |
| ded | Dr. Engrave Document |
| des | Intuit QuickBooks Template |
| des | OpenVSP v2 VSP Design Document |
| design | Microsoft Expression Design Drawing |
| dfb | Data Flask Formula |
| dfd | Silverrun DFD Document |
| dff | RenderWare 3D Model |
| dfg | Data Flask Grid |
| dfm | Help and Manual eBook Template |
| dft | Solid Edge Draft Document |
| dfti | FlexiWrite Document |
| dfx | Softdesk Drafix CAD Document |