Changes

* Building parts must be '''"connected to ground"''' and can have the following '''properties''' ( for example, storeys are no building parts ):

* Building parts must be '''"connected to ground"''' and can have the following '''properties''' ( for example, storeys are no building parts ):

** Building parts may have different '''building attributes''' ( e.g. function, roof type ),

** Building parts may have different '''building attributes''' ( e.g. function, roof type ),

** Building parts may have a address that '''differs''' from the address of the building,

** Building parts may have an address that '''differs''' from the address of the building,

** The geometry of building parts (''bldg:BuildingParts'') must be modeled in a way that both the '''volume''' and the '''surfaces''' of the boundary surfaces ( wall surfaces, roof surfaces and ground surfaces ) correspond to the real conditions ([[#BuildingPart/Geometry|see chapter Building Part/Geometry]]),

** The geometry of building parts (''bldg:BuildingParts'') must be modeled in a way that both the '''volume''' and the '''surfaces''' of the boundary surfaces ( wall surfaces, roof surfaces and ground surfaces ) correspond to the real conditions ([[#BuildingPart/Geometry|see chapter Building Part/Geometry]]),

** If a building part is emphasized as the '''main part of the building''', its semantics and geometry can be modeled in the parent building,

** If a building part is emphasized as the '''main part of the building''', its semantics and geometry can be modeled in the parent building,