definition
strict definition
lot number
The cadastral number of the parcel of land a building stands on, as issued by the responsible land register.
A lot number identifies the parcel, not the building. It comes from the local land register, which is why the format differs from country to country and the value is kept as text: 17-2-20-04-09-102-016 is one real example.
A building can stand on more than one parcel. The primary number names the parcel the building is registered under, and a secondary number is recorded where it covers further ground.
Because it names land rather than a structure, a lot number survives a demolition and is reused by whatever is built next. It is not a building identifier.