| rdi | SPEFO Differential Spectrum Data |
| rdic | StarDict Dictionary Resource |
| rdj | JCanyon Texture Data |
| rdl | Bentley MicroStation Redline Data |
| rdm | Remote Desktop Manager Session Data |
| rdmj | Remote Desktop Manager Session Data |
| rdml | Real-time PCR Data Markup Language Data |
| rdn | Carlson 2016 Road Network Data |
| rdo | Oracle Database Redo Log |
| rdox | Reflection Desktop Session Data |
| rdr | Dynamic Report Decoder File |
| rds | WAsP v4 Roughness Description |
| rdt | Adobe Captivate RoboDemo Template |
| rdx | Borland Reflex Data File |
| rdy | Ready Pro Accounting Data |
| rdy | TSP-INet Server Acknowledge Data |
| rdz | RemoteDocs Encrypted Document |
| re1 | Hy-Tek Meet Manager Registration Data |
| re2 | NEK5000 Re2file |
| re3 | Honeywell HNDR-S4824 Backup Data |
| re4 | RomEditor4 Binary Data |
| rea | NEK5000 Reafile |
| readyboot | ReadyBoot Data |
| real | Gnome Desktop Data |
| reality | RealityKit 3D Scene |
| reals | ScadaWorks Real Bank Template |
| reapeaks | REAPER Media Peak Information |
| reapindex | REAPER Media Peak Index |
| rec | ARCserve Archivation Protocol Data |
| rec | Easy CD Creator Recovery Data |
