The documentation states:
22.214.171.124 Spatial Composition
The order of spatial structure elements being included in the concept for builing projects are from high to low level: IfcProject, IfcSite, IfcBuilding, IfcBuildingStorey, and IfcSpace with IfcSite, IfcBuildingStorey and IfcSpace being optional levels. Therefore an spatial structure element can only be part of an element at the same or higher level.
In addition a more general hierarchical tree of spatial elements can be created by using IfcSpatialZone, from high to low: IfcProject, IfcSite, and IfcSpatialZone with IfcSite being an optional level.
- Can someone clarify the intention for IfcSpatialZone? Does this mean that IfcSpatialZone must either belong to an IfcSite or an IfcProject and nothing else? What does the second paragraph mean?
- Why is IfcExternalSpatialElement not mentioned at all? Where does it fit in the hierarchy? Is it hierarchical? I assume it is, as I haven’t read otherwise. Is it an optional level? I also assume it is. Common sense tells me it is an optional level that must either belong to an IfcSite or IfcProject, but I cannot find anything about this in the spec.