| rdoc | Ruby RDoc Document |
| rdoff | NASM Relocatable Dynamic Object File Format Data |
| rdv | NTgraph Borland C 32 Data |
| re | Python Regular Expressions Source Code |
| re | Reason Module |
| reb | REBOL Source Code |
| red | Modula-2 Path Info |
| red | XRK Redcode Source Code |
| reflector | .NET Reflector Data |
| refresh | Visual Studio Refresh Data |
| regi | Kagi Registration Module Data |
| regmap | Altera Quartus II Register Map Information |
| rei | Reason Module Interface |
| rel | PDP-10 Relocatable Object |
| rel | Retrieve 4GL Dataset |
| reloc | Windows PE Relocation Section |
| rep | WinDev HyperFileSQL REP File |
| res | Godot Engine Binary Resource Data |
| res | Windows Resource File |
| resjson | Microsoft Edge JavaScript Resources Data |
| resources | Visual Studio .NET Resources Data |
| resx | ASP.NET Resource |
| rexx | IBM REXX Source Code |
| rgs | Windows Registration Script |
| rgss2a | RPG Maker VX RGSS Encrypted Archive |
| rgss3a | RPG Maker VX RGSS Encrypted Archive |
| rgssad | RPG Maker VX RGSS Encrypted Archive |
| rgx | ReaGeniX Code Generator Symbol Table |
| rh | Borland C++ Resource Header |
| rhistory | R History Data |
| rho | Rholang Source Code |
| rhtml | Erubis Script |
| rhtml | eRuby HTML Web Page |
| ridl | Restricted Interface Definition Language Data |
| rin | Retrieve 4GL Database Index |
