8.14.3.9 IfcPresentationLayerAssignment

RV ⓘ

AbV ⓘ

8.14.3.9.1 Semantic definition

The presentation layer assignment provides the layer name (and optionally a description and an identifier) for a collection of geometric representation items. The IfcPresentationLayerAssignment corresponds to the term "CAD Layer" and is used mainly for grouping and visibility control.

Visibility and access control and layer style assignment (colour, line style, line width) is handled by the subtype IfcPresentationLayerWithStyle.

{ .use-head} Attribute use definition

Figure A illustrates assignment of items by shape representation or representation item. The set of AssignedItems can either include a whole shape representation, or individual geometric representation items. If both, the IfcShapeRepresentation has a layer assignment, and an individual geometric representation item in the set of IfcShapeRepresentation.Items, then the layer assignment of the IfcGeometricRepresentationItem overrides the layer assignment of the IfcShapeRepresentation.

instantiation diagram — Figure A — Presentation layer assignment

8.14.3.9.2 Entity inheritance

8.14.3.9.3 Attributes

#	Attribute	Type	Description
IfcPresentationLayerAssignment (4)
1	Name	IfcLabel	Name of the layer.
2	Description	OPTIONAL IfcText	Additional description of the layer.
3	AssignedItems	SET [1:?] OF IfcLayeredItem	The set of layered items, which are assigned to this layer.
4	Identifier	OPTIONAL IfcIdentifier	An (internal) identifier assigned to the layer.

Table B

8.14.3.9.4 Formal propositions

Name Description

ApplicableItems

Name	Description
ApplicableItems	The items within the set of AssignedItems that can be assigned to a presentation layer shall be geometric shape representation or representation items. IFC4-CHANGE The where rule has been added.
`SIZEOF(QUERY(temp <* AssignedItems \| ( SIZEOF(TYPEOF(temp) * [ 'IFC4X4_DEV_20260525.IFCSHAPEREPRESENTATION', 'IFC4X4_DEV_20260525.IFCGEOMETRICREPRESENTATIONITEM', 'IFC4X4_DEV_20260525.IFCMAPPEDITEM']) = 1) )) = SIZEOF(AssignedItems)`

The items within the set of AssignedItems that can be assigned to a presentation layer shall be geometric shape representation or representation items.

SIZEOF(QUERY(temp <* AssignedItems | (
SIZEOF(TYPEOF(temp) * [
'IFC4X4_DEV_20260525.IFCSHAPEREPRESENTATION',
'IFC4X4_DEV_20260525.IFCGEOMETRICREPRESENTATIONITEM',
'IFC4X4_DEV_20260525.IFCMAPPEDITEM']) = 1)
)) = SIZEOF(AssignedItems)

Table C

8.14.3.9.5 Formal representation

ENTITY IfcPresentationLayerAssignment
SUPERTYPE OF (ONEOF
(IfcPresentationLayerWithStyle));
Name : IfcLabel;
Description : OPTIONAL IfcText;
AssignedItems : SET [1:?] OF IfcLayeredItem;
Identifier : OPTIONAL IfcIdentifier;
WHERE
ApplicableItems : SIZEOF(QUERY(temp <* AssignedItems | (
SIZEOF(TYPEOF(temp) * [
'IFC4X4_DEV_20260525.IFCSHAPEREPRESENTATION',
'IFC4X4_DEV_20260525.IFCGEOMETRICREPRESENTATIONITEM',
'IFC4X4_DEV_20260525.IFCMAPPEDITEM']) = 1)
)) = SIZEOF(AssignedItems);
END_ENTITY;