8.18.3.10 IfcRepresentation

ABSTRACT This definition may not be instantiated

8.18.3.10.1 Semantic definition

The IfcRepresentation defines the general concept of representing product properties and in particular the product shape.

Representation Use Definition

Each representation, either IfcShapeRepresentation, or IfcTopologyRepresentation shall have a well defined:

ContextOfItems: Reference to an IfcGeometricRepresentationContext as agreed for this representation.
RepresentationIdentifier: Name of the representation, for example, 'Body' for 3D shape, 'FootPrint' for 2D ground view, 'Axis' for reference axis.
RepresentationType: Name for the geometric, or topological representation type, for example, 'SweptSolid' for 3D swept solids, 'Brep' for boundary representation.

8.18.3.10.2 Entity inheritance

8.18.3.10.3 Attributes

#	Attribute	Type	Description
IfcRepresentation (7)
1	ContextOfItems	IfcRepresentationContext	Definition of the representation context for which the different subtypes of representation are valid.
2	RepresentationIdentifier	OPTIONAL IfcLabel	The optional identifier of the representation as used within a project.
3	RepresentationType	OPTIONAL IfcLabel	The description of the type of a representation context. The representation type defines the type of geometry or topology used for representing the product representation. More information is given at the subtypes IfcShapeRepresentation and IfcTopologyRepresentation. The supported values for context type are to be specified by implementers agreements.
4	Items	SET [1:?] OF IfcRepresentationItem	Set of geometric representation items that are defined for this representation.
	RepresentationMap	SET [0:1] OF IfcRepresentationMap FOR MappedRepresentation	Use of the representation within an IfcRepresentationMap. If used, this IfcRepresentation may be assigned to many representations as one of its Items using an IfcMappedItem. Using IfcRepresentationMap is the way to share one representation (often of type IfcShapeRepresentation) by many products. IFC2x3-CHANGE The inverse attribute LayerAssignments has been added
	LayerAssignments	SET [0:?] OF IfcPresentationLayerAssignment FOR AssignedItems	Assignment of the whole representation to a single or multiple layer(s). The LayerAssigments can be overridden by LayerAssigments of the IfcRepresentationItem's within the list of Items. NOTE Implementation agreements can restrict the maximum number of layer assignments to 1. IFC2x3-CHANGE The inverse attribute LayerAssignments has been added
	OfProductRepresentation	SET [0:?] OF IfcProductRepresentation FOR Representations	Reference to the product representations to which this individual representation applies. In most cases it is the reference to one or many product shapes, to which this shape representation is applicable. IFC4-CHANGE Inverse relationship cardinality relaxed to be 0:N.

Table 8.18.3.10.A

8.18.3.10.4 Formal representation

ENTITY IfcRepresentation
 ABSTRACT SUPERTYPE OF (ONEOF
	(IfcShapeModel
	,IfcStyleModel));
	ContextOfItems : IfcRepresentationContext;
	RepresentationIdentifier : OPTIONAL IfcLabel;
	RepresentationType : OPTIONAL IfcLabel;
	Items : SET [1:?] OF IfcRepresentationItem;
 INVERSE
	RepresentationMap : SET [0:1] OF IfcRepresentationMap FOR MappedRepresentation;
	LayerAssignments : SET [0:?] OF IfcPresentationLayerAssignment FOR AssignedItems;
	OfProductRepresentation : SET [0:?] OF IfcProductRepresentation FOR Representations;
END_ENTITY;