Aggregates shall have more than one part
Based on IFC2x3
Initiator ISG Meeting-Budapest
Effects Coordination View 2.0
Date 2011 10 24
All elements and element types that are exported as an aggregate*) shall have more than one component. The IfcRelAggregates relationship pointing to the subtype of IfcElement being the container element shall therefore have two or more RelatedObjects.
NOTE In exceptional cases an aggregate may have only one component, therefore it is reported as a warning within the validation process. On import software applications shall accept aggregates with one or more components.
*) An aggregate is a subtype of IfcElement or IfcElementType having the (INV) relationship IsDecomposedBy established and pointing to an IfcRelAggregates relationship