| dgrp | Retro Studios Dependency Group |
| dgsl | Directed Graph Shader Language Data |
| dgx | IBM Rational XDE Diagram |
| di | D Language Source Code |
| diagsession | Microsoft Visual Studio Diagnostic Session Data |
| dif | ProWorx NXT Data Interchange File |
| dill | Dart Compiled Binary |
| din | DataEase Installation Script |
| dip | Crestron SIMPL IP Table Data |
| disco | Visual Studio .NET Discovery Data |
| discomap | Visual Studio .NET Discovery Map Data |
| discordbot | Discord Bot Maker Project |
| dj | DJGPP Source Code |
| dj2 | DJGPP Source Code |
| djg | DJGPP Makefile |
| dl3 | VS10XX VSOS Application |
| dlct | AppleScript Dialect Data |
| dldi | libfat Dynamically Linked Device Interface |
| dlg | Visual C++ Dialog |
| dlk | Transputer Development System Occam Compiler Link Info |
| dm | BYOND Dream Maker Source Code |
| dm1 | ER/Studio Data Model |
| dm2 | Toad Data Modeler 2 Data |
| dmb | BYOND Dream Maker Compiled World |
| dmd | Domain Model Definition |
| dmd | SQL Developer Data Modeler Design |
| dmdl | Asakusa Framework DMDL Model Data |
| dmdz | SQL Developer Data Modeler Design |
| dml | PowerDynamo Dynascript Script |
| dmm | BYOND Dream Maker Map |
| dmp | PDP-10 Core Dump |
| dmt | Delphi Menu Template |
| dmx | Microsoft SQL Server Data Mining Extension |
| dni | IAR System Debugger Initialization Data |
| dnx | IBM Rational Software Architect DNX Diagram |
