ISO 4157 is an
ISOstandard for construction drawings and designation systems.
It is composed of 3 parts:
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"
Main definitions:
Floor n: is the horizontal partition between storey n and storey (n+1). The floor in storey 5 is named as floor 4.
Room: identifiable physical space (area or volume, space or void) real or theoretical, although not necessary a traditional room (i.e., enclosed by walls, ceiling and floor).