Based on IFC2x3
Initiator Official buildinSMART IFC2x3 CV2.0 certification programme
Effects Coordination View 2.0
Date 2010 09
If an IfcElement is a part of another IfcElement (the container) through the relationship IfcRelAggregates, then the relative placement of that IfcElement shall be provided by an IfcLocalPlacement with an PlacementRelTo attribute pointing to the IfcLocalPlacement of the container element.