| dfm | Delphi Form |
| dfn | Delphi Definition File |
| dft | Dyalog APL Format Data |
| dg | DataFlex Dialog Box Source Code |
| dg5 | DGLux5 Page |
| dgd | DGD Program |
| dge | Micro Focus Studio Declaration Generator Batch File |
| dgml | Directed Graph Markup Language Document |
| 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 |
| dic | WebDev Dictionary Data |
| dif | ProWorx NXT Data Interchange File |
| dill | Dart Compiled Binary |
| din | DataEase Installation Script |
| Dyalog APL Input Table |
| dip | Crestron SIMPL IP Table Data |
| dir | WebSTAR Directory Indexer Plugin |
| dis | DisSharp Project |
| 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 |
| dlf | Dyalog APL Session Log |
| dlg | RadASM Dialog Data |
| 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 |
| SQL Developer Data Modeler Design |
| Visual dBASE Data Module |
| dmdl | Asakusa Framework DMDL Model Data |
| dmdz | SQL Developer Data Modeler Design |
| dml | Medical Manager DML System Script |
| PowerDynamo Dynascript Script |
| dmm | BYOND Dream Maker Map |
| dmp | BYOND Dream Maker Map Data |
| PDP-10 Core Dump |
| dms | BYOND Dream Maker Script |
| dmt | Delphi Menu Template |
| dmx | Medical Manager DML System Index |
| Microsoft SQL Server Data Mining Extension |
| dni | IAR System Debugger Initialization Data |
| dnx | IBM Rational Software Architect DNX Diagram |
| do | Stata Batch File |
| dob | Visual Basic User Document Form |
| docbook | DocBook Document |
| docset | Doxygen Document Set File |
| docstates | Visual Studio Document Tab State Data |
| dof | Delphi Option File |
| doh | Geoworks GEOS Dependency Information |
| dol | Uniface Global Object Data |
| dot | Dyalog APL Output Table |
| dotfuproj | Microsoft Visual Studio Dotfuscator Project |
| dotsettings | Visual Studio Solution Settings Data |
| dox | Doxygen DOX Data |
| Visual Basic ActiveX Document Binary Form |
| doxy | Doxygen Data |
| dpb | ProWorx NXT Descriptor Pointer with Blocking |
| dpc | Delphi Package Collection |
| dpd | ABC Dyadic Predicate Data |
| dpf | ProWorx NXT Descriptor Pointer |
| dpj | Java Source Code Dependency Data |
| dpk | Delphi Package |
| dpkw | Delphi Package for Windows |
| dpl | Delphi Package Library |
| WinDev Duplicate Data |
| dplt | AppleScript Droplet |
| dpmi | DOS Protected-Mode Interface Data |
| dpo | Delphi Object Repository |
