| Abbreviation | Definition |
|---|---|
| PPNX | PCS Phosphate |
| PPRX | Phillips Petroleum |
| PPSX | Pioneer Pipe and Supply |
| PPSX | Pioneer Pipe and Supply Company Incorporated |
| PPTX | PCS Phosphate |
| PPTX | PCS Phosphate Company |
| PPU | Peoria and Pekin Union Railway |
| PPU | Peoria and Pekin Union Railway Company |
| PQCX | P Q Corporation |
| PQCX | PQ Corporation |
| PQRS | Plasser Quick Relaying System |
| PQX | PQ Corporation |
| PRASA | Passenger Rail Agency of South Africa |
| PRAX | First Union Rail |
| PRAX | Pacific Rail Leasing Corp (First Union Rail) |
| PRBX | Trinity Rail Management |
| PRBX | Trinity Rail Management Incorporated |
| PRCL | Pipavav Railway Corporation Ltd. |
| PRCX | 20th Century Fox |
| PRCX | Prairie Coal Limited |