IFC 4.3.0.1 (IFC4X3_TC1)

# 5.1.3.35 IfcRelDecomposes

ABSTRACT This definition may not be instantiated

## 5.1.3.35.1 Semantic definition

The decomposition relationship, IfcRelDecomposes, defines the general concept of elements being composed or decomposed. The decomposition relationship denotes a whole/part hierarchy with the ability to navigate from the whole (the composition) to the parts and vice versa.

Decompositions may be constrained by requiring both, the whole and its parts, to be of the same type - thus establishing a nesting relationship. Or they may require some form of physical containment, thus establishing special types of aggregation relationships.

Decompositions imply a dependency, i.e. the definition of the whole depends on the definition of the parts and the parts depend on the existence of the whole. The decomposition relationship can be applied in a recursive manner, i.e. a decomposed element can be part in another decomposition. Cyclic references have to be prevented at application level.

## 5.1.3.35.5 Formal representation

ENTITY IfcRelDecomposes
ABSTRACT SUPERTYPE OF (ONEOF
,IfcRelAggregates
,IfcRelNests
,IfcRelProjectsElement
,IfcRelVoidsElement))
SUBTYPE OF (IfcRelationship);
END_ENTITY;

## 5.1.3.35.6 References

### 5.1.3.35.7 Changelog

#### 5.1.3.35.7.1 IFC4

• attribute, RelatedObjects
• attribute, RelatingObject
• where rule, WR31