| red | CARE-S InfoWorks Rainfall Data |
| ref | PLINK Long-format Reference Allele File |
| ref | RFSCAT Simulator Wind Field Reference Data |
| ref | WinPLOTR Refined Parameters Data |
| reference | Budget In Brief Reference Data |
| refx | E-Sword Reference Library Note Data |
| reg-auto | WOW! Diagnostic Registration Data |
| regkey | Zoom Player Registration Key Data |
| regularizer | SAM Transition Regularizer Data |
| rek | Fraunhofer EZRT Volume Data |
| rel | my Knowledge Relation Data |
| rel | PLINK Text Relationship Matrix |
| remotemap | Reason Remote Mapping Data |
| 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 |
| 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 |