| Abbreviation | Definition |
|---|---|
| RESX | Rescar |
| RESX | Rescar Incorporated |
| RET | Recordall Electronic Transmitter |
| RETB | Radio Electronic Token Block |
| RFCX | R&F Coal |
| RFDC | Rail Finance and Development Corporation |
| RFG | Rail Freight Group |
| RFMX | Caldwell- Baker Company |
| RFMX | Robert F. Miller (Coldwell-Baker) |
| RFP | CSX Transportation Incorporated |
| RFP | Richmond, Fredericksburg and Potomac Railroad (CSX Transportation) |
| RFPC | Railroad Friction Products Corporation |
| RFPU | CSX Transportation Incorporated |
| RFPU | Richmond, Fredericksburg and Potomac Railroad (CSX Transportation) |
| RFPZ | CSX Transportation Incorporated |
| RFPZ | Richmond, Fredericksburg and Potomac Railroad (CSX Transportation) |
| RFRU | Rain For Rent |
| RFRX | Rick Franklin Corporation |
| RGCX | Rio Grande Chemical Sales |
| RGCX | Rio Grande Chemical Sales Company |