| rbn | Richard's Bridge Notation Data |
| rbr | libigl ReAntTweakBar Data |
| rbsct | RegexBuddy Source Code Template |
| rbt | Xilinx Raw BIT Data |
| rbtx | Lego Mindstorms NXT Create Pack and Go File |
| rbuistate | Real Studio UI State Data |
| rbv | GrafNav Exported Binary Values Data |
| rc1 | Samsung S5230 Firmware RSRC1 File |
| rc2 | Samsung S5230 Firmware RSRC2 File |
| rca | RCA Anaesthetic Logbook Document |
| rcb | Ripple Chat Bot Data |
| rcd | Symantec pcAnywhere Recorded Session |
| rcg | Recog Character Recognition Set |
| rch | SWAT Reach Output Data |
| rch | MODFLOW Recharge Package |
| rci | SPEFO Rectified Cleaned Data |
| rcj | Robocopy Job Data |
| rck | REScheck Data |
| rcl | Reflection Command Language Script |
| rcn | QRacing Track Records Data |
| rco | PlayStation Portable Resource Data |
| rcq | RESTClient Requests File |
| rcr | SAP Business One XL Reporter Data |
| rctd | RabbitCT Dataset |
| rcut | Webinaria Recording Cut |
| rcw | RaceSail Regatta Data File |
| rd | Reaction Data File |
| rd1 | DATAIR Retirement Plan Document System Data |
| rd3f | Ray Dream 3D Data |
| rd3x | Reflection Desktop Session Data |
| rd4a | Ray Dream 3D v4 Animation |
| rd5x | Reflection Desktop Session Data |
| rda | Siemens MR Spectroscopy ASCII Data |
| rda | Oracle Database Storage Area |
| rdat | RNA Data |