| Abbreviation | Definition |
|---|---|
| COLZ | XTRA Intramodal |
| COMX | Commonwealth Edison |
| CONU | Contrans |
| CONX | Conoco Inc. |
| CONX | Conoco Incorporated |
| COOK | Cook Transit |
| COOK | Cook Transit Railroad |
| COOX | Cooperative Producers (First Union Rail) |
| COOX | First Union Rail |
| COP | City of Prineville Railway |
| COPX | CanadianOxy Industrial Chemicals |
| COPX | CanadianOxy Industrial Chemicals Limited |
| CORP | Central Oregon and Pacific Railroad |
| CORP | Central Oregon and Pacific Railroad Incorporated |
| CORU | CATU Containers |
| CORU | CATU Containers S. A. |
| CORX | Coors Brewing |
| CORX | Coors Brewing Company |
| COSU | China Ocean Steamship ( Coscon ContaineLines) |
| COSU | China Ocean Steamship Limited |