B area type:
(usually used)

The gross floor area and gross room volume are included in subsequent evaluations and analyses.

The gross room volume (GRV) is the volume of the building
which is enclosed by the foundation at the bottom
and by the outer boundaries on the other sides

The gross floor area is the sum of the base areas of all the floor levels in a building.
Covering (e.g. plaster) is to be included in dimensions used for calculations.

M area type

With this setting, the gross croom volume is included in subsequent evaluations and analyses; the gross floor area, however, is ignored.

U area type
(empty space)

Empty space; neither gross floor area nor gross room volume is included in subsequent evaluations and analyses.

V area type

Not used, not empty