IfcPresentationLayerAssignment

Semantic definitions at the entity

Entity 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.

NOTE The use of presentation layer shall be restricted to simple grouping and displaying purposes.

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

NOTE Corresponding ISO 10303 name: presentation layer assignment. Please refer to ISO/IS 10303-46:1994, p. 36 for the final definition of the formal standard.

HISTORY New entity in IFC2x2.

Attribute use definition

Figure 377 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 overides the layer assignment of the IfcShapeRepresentation.

Figure 377 — Presentation layer assignment

Attribute definitions

#	Attribute	Type	Cardinality	Description	C
1	Name	IfcLabel	[1:1]	Name of the layer.	X
2	Description	IfcText	[0:1]	Additional description of the layer.	X
3	AssignedItems	IfcLayeredItem	S[1:?]	The set of layered items, which are assigned to this layer.	X
4	Identifier	IfcIdentifier	[0:1]	An (internal) identifier assigned to the layer.	X

Formal Propositions

Rule	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.

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	C
IfcPresentationLayerAssignment
1	Name	IfcLabel	[1:1]	Name of the layer.	X
2	Description	IfcText	[0:1]	Additional description of the layer.	X
3	AssignedItems	IfcLayeredItem	S[1:?]	The set of layered items, which are assigned to this layer.	X
4	Identifier	IfcIdentifier	[0:1]	An (internal) identifier assigned to the layer.	X

Formal representations

XSD Specification

 <xs:element name="IfcPresentationLayerAssignment" type="ifc:IfcPresentationLayerAssignment" substitutionGroup="ifc:Entity" nillable="true"/>

 <xs:complexType name="IfcPresentationLayerAssignment">

  <xs:complexContent>

   <xs:extension base="ifc:Entity">

    <xs:sequence>

     <xs:element name="AssignedItems">

      <xs:complexType>

       <xs:group ref="ifc:IfcLayeredItem" maxOccurs="unbounded"/>

       <xs:attribute ref="ifc:itemType" fixed="ifc:IfcLayeredItem"/>

       <xs:attribute ref="ifc:cType" fixed="set"/>

       <xs:attribute ref="ifc:arraySize" use="optional"/>

      </xs:complexType>

     </xs:element>

    </xs:sequence>

    <xs:attribute name="Name" type="ifc:IfcLabel" use="optional"/>

    <xs:attribute name="Description" type="ifc:IfcText" use="optional"/>

    <xs:attribute name="Identifier" type="ifc:IfcIdentifier" use="optional"/>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcPresentationLayerAssignment

 SUPERTYPE OF(IfcPresentationLayerWithStyle);

  Name : IfcLabel;

  Description : OPTIONAL IfcText;

  AssignedItems : SET [1:?] OF IfcLayeredItem;

  Identifier : OPTIONAL IfcIdentifier;

 WHERE

  ApplicableItems : SIZEOF(QUERY(temp <* AssignedItems | (
  SIZEOF(TYPEOF(temp) * [
    'IFCREPRESENTATIONRESOURCE.IFCSHAPEREPRESENTATION',
    'IFCGEOMETRYRESOURCE.IFCGEOMETRICREPRESENTATIONITEM',
    'IFCGEOMETRYRESOURCE.IFCMAPPEDITEM']) = 1)
)) = SIZEOF(AssignedItems);
END_ENTITY;

 EXPRESS-G diagram

	Zuordnung zu Präsentations-Layer
	Presentation Layer Assignment
	Assignation de calque