ISO 4157

• ISO 4157-1:1998 "Construction drawings -- Designation systems -- Part 1: Buildings and parts of buildings"
• ISO 4157-2:1998 "Construction drawings -- Designation systems -- Part 2: Room names and numbers"
• ISO 4157-3:1998 "Construction drawings -- Designation systems -- Part 3: Room identifiers"

• Floor n: is the horizontal partition between storey n and storey. The floor in storey 5 is named as floor 4.
• Room: identifiable physical space real or theoretical, although not necessary a traditional room.
• Room identifiers: registration number of spaces:
• Room numbers: numbers of rooms