| Abbreviation | Definition |
|---|---|
| FLNX | R. P. Flynn Incorporated - Ohio Railway Supply |
| FLOX | Flex Leasing |
| FLOX | Flex Leasing Corporation |
| FLR | Florida Lambda Rail |
| FLRX | ADM Milling |
| FLRX | ADM Milling Company |
| FLSX | Great Miami (Silver Star Enterprises) |
| FLSX | Great Miami Incorporated |
| FLT | Foss Launch and Tug |
| FLTZ | Flexi-Van Leasing |
| FLXU | Flexi-Van Containers/Chassis |
| FLXU | Flexi-Van Leasing |
| FLXZ | Flexi-Van Leasing |
| FLXZ | Flexi-Van Leasing Incorporated |
| FMCU | FMC Corporation (Industrial Chemical Group) |
| FMCU | FMC Corporation Industrial Chemical Group |
| FMGU | Flota Mercante Grancolombiana |
| FMGU | Flota Mercante Grancolombiana, S. A. |
| FMID | Florida Midland Railroad |
| FMID | Florida Midland Railroad Company Incorporated |