| 1 | IOCA | IOC TRUCKING | | | SCAC4 |
| 2 | IOCB | INFINITO INC | | | SCAC4 |
| 3 | IOCC | QUEBEC NORTH SHORE & LABRADOR | | | PWRC |
| 4 | IOCC | INDEPENDENT OIL & COAL COMPANY | | | SCAC4 |
| 5 | IOCM | IRMAS CREATIONS | | | SCAC4 |
| 6 | IOCP | INDEPENDENT OIL COMPANY | | | SCAC4 |
| 7 | IOCR | The Indiana & Ohio Ry. | added 7/2005; 7/2005 | | NAKINA |
| 8 | IOCR | The Indiana & Ohio Central R.R. | added 7/1999; 7/2000; eliminated 7/2005 | | NAKINA |
| 9 | IOCR | The Indiana & Ohio Rail System | eliminated 7/1999 | | NAKINA |
| 10 | IOCR | The Indiana & Ohio Central R.R., Inc. | added 1/1988; 1/1994 | | NAKINA |
| 11 | IOCR | The Indiana & Ohio Central R.R., Inc. | added 1/88; 1/94 | | NRHS |
| 12 | IOCR | The Indiana & Ohio Rail System | eliminated 7/99 | | NRHS |
| 13 | IOCR | The Indiana & Ohio Central R.R. | added 7/99; 7/2000 | | NRHS |
| 14 | IOCR | INDIANA & OHIO RAILWAY [INDIANA & OHIO CENTRAL RAILROAD, INC] | | | PWRC |
| 15 | IOCR | Indiana and Ohio Central Railroad | | | RSRV |
| 16 | IOCT | INTEROCEAN TRADE AND TRANSPORTATION | | | SCAC4 |
| 17 | IOCX | Rail Enterprises, Inc. | added 10/1997; eliminated 4/1998; 7/2000-7/2005 (not listed) | | NAKINA |
| 18 | IOCX | Illinois Oil Co. | 8/1920-1/1945 | | NAKINA |
| 19 | IOCX | Illinois Oil Co. | Apr-38 | | NRHS |
| 20 | IOCX | Rail Enterprises, Inc. | added 10/97; eliminated 4/98; 7/2000 | | NRHS |
| 21 | IOCX | *ILLINOIS OIL CO.. | | | PWRC |
| 22 | IOCX | +RAIL ENTERPRISES INCORPORATED | | | PWRC |
| 23 | IOCX | Illinois Oil Co. (Rail Enterprises) | | | RSRV |
| 24 | IOCX | RAIL ENTERPRISES INC (ACTING AGENT | | | SCAC4 |
| 25 | IOCY | IOC COMPANY LLC | | | SCAC4 |
