# 5.4.3.57 IfcRelReferencedInSpatialStructure

## 5.4.3.57.1 Semantic definition

The objectified relationship, IfcRelReferencedInSpatialStructure is used to assign elements in addition to those levels of the project spatial structure, in which they are referenced, but not primarily contained. It is also used to connect a system to the relevant spatial element that it serves.

Any element can be referenced to zero, one or several levels of the spatial structure. Whereas the IfcRelContainedInSpatialStructure relationship is required to be hierarchical (an element can only be contained in exactly one spatial structure element), the IfcRelReferencedInSpatialStructure is not restricted to be hierarchical.

Predefined spatial structure elements to which elements can be assigned are

Elements can also be references in a spatial zone that is provided as IfcSpatialZone.

Figure 5.4.3.57.A shows the use of IfcRelContainedInSpatialStructure and IfcRelReferencedInSpatialStructure to assign an IfcCurtainWall to two different levels within the spatial structure. It is primarily contained within the ground floor, and additionally referenced within the first and second floor.

## 5.4.3.57.6 Formal representation

ENTITY IfcRelReferencedInSpatialStructure
SUBTYPE OF (IfcRelConnects);
RelatedElements : SET [1:?] OF IfcSpatialReferenceSelect;
RelatingStructure : IfcSpatialElement;
WHERE
AllowedRelatedElements : SIZEOF(QUERY(temp <* RelatedElements | ('IFC4X3_DEV_9f90c1f0.IFCSPATIALSTRUCTUREELEMENT' IN TYPEOF(temp)) AND (NOT ('IFC4X3_DEV_9f90c1f0.IFCSPACE' IN TYPEOF(temp)))
)) = 0;
END_ENTITY;