| renderman | RenderMan Data |
| renv | Rhino 3D Saved Environment Data |
| rep | Act! Report Data |
| repx | XtraReports Report Definition |
| res | 4D Database Client Resource Data |
| res | Abaqus/Standard Restart Data |
| res | Qualitek-4 Results Data |
| res | SHELX Chemical Model RES Data |
| res | SWAT Reservoir Input Data |
| res11 | MIKE 11 DSF Results Data |
| resbuild | ResBuild Data |
| reso | HEADTAIL Resonator Data |
| resp | IRIS RESP File |
| respack | NFE Tools Resource Pack |
| resu | Salome-Meca Exported Results Data |
| resw | Microsoft Windows Resources Data |
| reu | C64 REU Image |
| rew | MRMC State Rewards Data |
| rewi | MRMC Impulse Rewards Data |
| rex | 4D Database Client Local Data |
| rf1 | Retirement Forecast Data |
| rf5 | Tektronix RFXpress RF5 Record Data |
| rfa | Autodesk Revit Family File |
| rfb | RoboForm Bookmark File |
| rfc | RoboForm Contact File |
| rfd | RockFlow Simulation Data |
| rfe | RockFlow Log |
| rff | Roproc Format File Data |
| rfg | iNTEGRATOR Data |
| rfh | iNTEGRATOR Householding Data |
| rfl8 | Avantes Avasoft v8 Reflectance Mode Data |
| rflw | Adobe Edge Reflow Data File |
| rfn | RoboForm Safenote File |
| rfo | RoboForm Option File |
| rfo | RockFlow Results Data |