Property:Has unit identifier
From Tyne and Wear Metro wiki
The unique identifier for a unit of rolling stock. Usually this is a number (like 4001 or 555001), but not always (such as for BL1 or MA-60)
The unique identifier for a unit of rolling stock. Usually this is a number (like 4001 or 555001), but not always (such as for BL1 or MA-60)