IFC Model Tree Heirarchies for Buildings

Users IFC
1

Where can I find examples of acceptable IFC heirarchical relationships below IfcBuildingStorey?

For example:

  1. Where does Ifc Zone sit in relation to IfcSpace and IfcBuildingStorey?
  2. Can there be sub entities below the main building element entities, e.g. IfcWall

Where do I find good examples sample files?

Many thanks