IFC 4.3.0.0 (IFC4X3) final

8.9.3.58 IfcRepresentationItem

ABSTRACT This definition may not be instantiated

8.9.3.58.1 Semantic definition

The IfcRepresentationItem is used within an IfcRepresentation (directly or indirectly through other IfcRepresentationItem's) to represent an IfcProductRepresentation. Most commonly these IfcRepresentationItem's are geometric or topological representation items, that can (but not need to) have presentation style information assigned.

In case that presentation style information is applied, it can be either applied by an IfcStyledItem, or by an assignment to an IfcPresentationLayerWithStyle. If both are present, and both style assignments include the same subtype of IfcPresentationStyle, then the style assigned by IfcStyledItem takes priority.

Figure 1 shows an instance diagram explaining the use of IfcStyledItem and IfcPresentationLayerWithStyle to apply presentation styles.

styles assigned by layer and styled item
Figure 8.9.3.58.B shows in instance diagram explaining the override of IfcPresentationLayerWithStyle by IfcStyledItem to apply presentation styles.
styles assigned by layer and styled item
Figure 8.9.3.58.B — Representation item style override

8.9.3.58.2 Entity inheritance

8.9.3.58.3 Attributes

# Attribute Type Description
IfcRepresentationItem (2)
LayerAssignment SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItems

Assignment of the representation item to a single or multiple layer(s). The LayerAssignments can override a LayerAssignments of the IfcRepresentation it is used within the list of Items.
StyledByItem SET [0:1] OF IfcStyledItem FOR Item

Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve.
Table 8.9.3.58.A

8.9.3.58.4 Formal representation 

ENTITY IfcRepresentationItem
 ABSTRACT SUPERTYPE OF (ONEOF
	(IfcGeometricRepresentationItem
	,IfcMappedItem
	,IfcStyledItem
	,IfcTopologicalRepresentationItem));
 INVERSE
	LayerAssignment : SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItems;
	StyledByItem : SET [0:1] OF IfcStyledItem FOR Item;
END_ENTITY;

8.9.3.58.5 References

8.9.3.58.6 Changelog