| Abbreviation | Definition |
|---|---|
| OHCR | Ohio Central Railroad |
| OHCR | Ohio Central Railroad Incorporated |
| OHFX | Fluor Daniel Fernald |
| OHIC | Ohi-Rail Corporation |
| OHKU | Ohka American |
| OHKU | Ohka American Incorporated USA |
| OHOX | U.S. Department of Energy Ohio Field |
| OHOX | United States Department of Energy Ohio Field |
| OHPA | Ohio and Pennsylvania Railroad |
| OHPA | Ohio and Pennsylvania Railroad Company |
| OHRY | Owego and Harford Railway |
| OHRY | Owego and Harford Railway Incorporated |
| OILX | GE Rail Services |
| OJGX | Oscar J. Glover |
| OJTX | Tauber Transportation |
| OKAN | Okanagan Valley Railway (OmniTRAX) |
| OKCE | Okarche Central Railway |
| OKCX | Lone Star Industries |
| OKCX | Lone Star Industries Incorporated |
| OKKT | Oklahoma, Kansas and Texas Railroad (Union Pacific Railroad) |