5.4.3.56 IfcRelProjectsElement

5.4.3.56.1 Semantic definition

The IfcRelProjectsElement is an objectified relationship between an element and one projection element that creates a modifier to the shape of the element. The relationship is defined to be a 1:1 relationship, if an element has more than one projection, several relationship objects have to be used, each pointing to a different projection element. The IfcRelProjectsElement establishes an aggregation relationship between the main element and a sub ordinary addition feature.

The IfcRelProjectsElement implies a Boolean operation of addition for the geometric bodies of the element and the feature element. As with all decomposition relationships it determines:

existence dependency - the RelatedFeatureElement cannot exist without the RelatingElement
hierarchical and non-cyclical relationship - the IfcRelProjectsElement can only alter a single IfcElement
no spatial containment - the IfcFeatureElementAddition as related element never participates in the hierarchical spatial containment relationship IfcRelContainedInSpatialStructure

5.4.3.56.2 Entity inheritance

- IfcRoot

5.4.3.56.3 Attributes

#	Attribute	Type	Description
IfcRoot (4)
1	GlobalId	IfcGloballyUniqueId	Assignment of a globally unique identifier within the entire software world.
2	OwnerHistory	OPTIONAL IfcOwnerHistory	Assignment of the information about the current ownership of that object, including owning actor, application, local identification and information captured about the recent changes of the object, NOTE Only the last modification is stored - either as addition, deletion or modification. IFC4-CHANGE The attribute has been changed to be OPTIONAL.
3	Name	OPTIONAL IfcLabel	Optional name for use by the participating software systems or users. For some subtypes of IfcRoot the insertion of the Name attribute may be required. This would be enforced by a where rule.
4	Description	OPTIONAL IfcText	Optional description, provided for exchanging informative comments.
Click to show 4 hidden inherited attributes
IfcRelProjectsElement (2)
5	RelatingElement	IfcElement	Element at which a projection is created by the associated IfcProjectionElement.
6	RelatedFeatureElement	IfcFeatureElementAddition	Reference to the IfcFeatureElementAddition that defines an addition to the volume of the element, by using a Boolean addition operation. An example is a projection at the associated element.

Table 5.4.3.56.A

5.4.3.56.4 Concept usage

Concept	Usage	Description
IfcRoot (2)
Revision Control	General	Ownership, history, and merge state is captured using IfcOwnerHistory.
Software Identity	General	IfcRoot assigns the globally unique ID. In addition it may provide for a name and a description about the concept.
Click to show 2 hidden inherited concepts

Table 5.4.3.56.B

5.4.3.56.5 Formal representation

 ENTITY IfcRelProjectsElement
 SUBTYPE OF (IfcRelDecomposes);
	RelatingElement : IfcElement;
	RelatedFeatureElement : IfcFeatureElementAddition;
END_ENTITY;