🔍 Key Concepts

• MMSI (Maritime Mobile Service Identity) structure and length • Difference between ship station, coast station, and group MMSIs • Meaning and use of the MID (Maritime Identification Digits)

💭 Think About

• Compare how many leading zeros each type of MMSI normally has (ship, coast, group). Do they all follow the same pattern? • Think about whether the MID always comes first in all MMSI types, or if sometimes zeros come before it. • Ask yourself: for coast stations, what is the required position of the MID within the 9 digits?

✅ Before You Answer

• Verify the standard format for a ship MMSI (where exactly the MID appears). • Verify the standard format for a coast station MMSI (how many zeros, and where the MID is placed). • Verify the standard format for a group MMSI (how many leading zeros, and where the MID appears).