| Abbreviation | Definition |
|---|---|
| DEF | SmartWare II Data definition |
| DEF | TLink - WLink Linker definition file |
| DEM | Demo |
| DEM | Digital Elevation Model |
| DEM | VistaPro Graphics file |
| DER | Internet security certificate |
| DES | Description |
| DESC | Description |
| DEV | Device driver |
| DF | NCSA Hierarchical Data File Bitmap graphics |
| DFD | Data Flow Diagram graphic |
| DFD | Dyadic functions (ABC programming language) |
| DFI | Digifont Outline font description |
| DFL | Default program settings (Signature) |
| DFM | Borland Delphi C++ Builder Form file |
| DFM | Data Flow diagram Model file |
| DFS | Delight Sound File |
| DFV | Printing form (MS Word) |
| DFX | Micrografx Effects DLL |
| DGN | MicroStation CAD drawing, vector format |