| dntu | DameWare NT Utilities Data |
| dnw | EMPOP DrawNetWork Data |
| dock | DragThing Dock Data |
| dockpack | Stardock ObjectDock Package |
| docktheme | Stardock ObjectDock Theme |
| docmenx | Egis Encrypted DOCM Data |
| docmeta | Bukkit Information Data |
| docstore | Adobe Photoshop Lightroom Documentum Cache |
| dod | Progress Artix Data Services Data Model |
| dods | Distributed Oceanographic Data System Data |
| doe | Arena Model File |
| doi | BiRT Data Object Instance |
| dol | Gamecube Executable DOL |
| dom | DIMPLOT Domain Definition |
| doms | SHERPA Domains Data |
| don | PLS-CADD Lines and Annotation Data |
| done | Cygwin Postinstall Data |
| dop | DOpus Toolbar File |
| dop | DxO Optics Pro Sidecar File |
| doq | Digital Orthophoto Quadrangle Data |
| dost | DoStudio Subtitle Format Data |
| dot | Ribbons Dot Definition |
| dotmenx | Egis Encrypted Word 2007 DOTM Document |
| dotxenx | Egis Encrypted Word 2007 DOTX Document |
| dov | BiRT Actuate Query Definition File |
| download | Partially Downloaded File |
| dp1 | DataPower Database |
| dp2 | DatePad 2 Data |
| dp4 | Actuate Analytics Cube Profile |
| dpatch | Dpatch Patch Data |
| dpb | DataPilot Data |
| dpcache | Apple iPhoto Desktop Photos Cache |
| dpe | DPwinEHE Calculation |
| dpf | COMPRESS Drafter Data |
| dpf | F-Secure Default Policy File |