IFC 4.3.x development

5.4.3.46 IfcRelProjectsElement

Change log

5.4.3.46.1 Semantic definitions at the entity

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.

NOTE  In contrary the IfcRelAggregates relationship established an aggregation of equal parts to a whole.

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 hiearchical spatial containment relationship IfcRelContainedInSpatialStructure

HISTORY  New entity in IFC2x2.

IFC4 CHANGE  Supertype changed to IfcRelDecomposes.

5.4.3.46.1 Attributes

#	Attribute	Type	Description
IfcRoot
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 in 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.
IfcRelationship
IfcRelDecomposes
IfcRelProjectsElement
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.

5.4.3.46.2 Entity inheritance

5.4.3.46.3 Definitions applying to General Usage

5.4.3.46.3.1 Identity

5.4.3.46.3.2 Revision Control

5.4.3.46.4 Formal representations

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