Numbering example for a complex shaped room. The entrance of room 19 [code: P01.L00.19] (red arrow) marks the first sub-room part (19.01). Ceilings have identification letters, starting with entrance ceiling (a) [code: P01.L00.19.01.Ca] and continuing (counterclockwise) with ceiling parts below the arch (b). The southern subdivision line (b) in been applied following a constructive division line (a pointed arch)