I've seen this done (in England) for blocks of flats where each floor has it's own postcode that matches the floor, eg ZZ1 Z1A through to ZZ1 Z1G (A-G for floor

I've seen this done (in England) for blocks of flats where each floor has it's own postcode that matches the floor, eg ZZ1 Z1A through to ZZ1 Z1G (A-G for floor 1 to 7).