The first 4 letters of the booking number indicate which ferry operator the booking number belongs to.
| Company | SCAC | Example | Additional Explanation |
| CLdN | CLVW | CLVW0012345678 | “CLVW” & “00” & booking number (8 positions) |
| DFDS | DFDS | DFDS12345678 | “DFDS” & booking number (8 positions) |
| P&O Ferries | PONF | PONFEU12345678 | “PONF” & “EU” & booking number (8 positions) |
| Stena Line | STNL | STNL0012345678 | “STNL” & “00” & booking number (8 positions) |