IfcPlacement

Semantic definitions at the entity

Entity definition

Definition from ISO/CD 10303-42:1992: A placement entity defines the local environment for the definition of a geometry item. It locates the item to be defined and, in the case of the axis placement subtypes, gives its orientation.

Additional definition from ISO/WD SC4/WG12/N071 Part42.2 geometry_schema: A placement locates a geometric item with respect to the coordinate system of its geometric context.

The IfcPlacement is an abstract supertype not to be directly instantiated, whereas the STEP P42 entity placement can be instantiated to define a placement without orientation. The derived attribute Dim has been added, see also note at IfcGeometricRepresentationItem.

NOTE: Corresponding STEP entity: placement. Please refer to ISO/IS 10303-42:1994, p. 27 for the final definition of the formal standard.

HISTORY: New entity in IFC Release 1.0

Attribute definitions

#	Attribute	Type	Cardinality	Description	A
1	Location	IfcCartesianPoint	[1:1]	The geometric position of a reference point, such as the center of a circle, of the item to be located.	X
	Dim :=Location.Dim	IfcDimensionCount	[1:1]	The space dimensionality of this class, derived from the dimensionality of the location.	X

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	A
IfcRepresentationItem
IfcGeometricRepresentationItem
IfcPlacement
1	Location	IfcCartesianPoint	[1:1]	The geometric position of a reference point, such as the center of a circle, of the item to be located.	X
	Dim :=Location.Dim	IfcDimensionCount	[1:1]	The space dimensionality of this class, derived from the dimensionality of the location.	X

Formal representations

XSD Specification

 <xs:element name="IfcPlacement" type="ifc:IfcPlacement" abstract="true" substitutionGroup="ifc:IfcGeometricRepresentationItem" nillable="true"/>

 <xs:complexType name="IfcPlacement" abstract="true">

  <xs:complexContent>

   <xs:extension base="ifc:IfcGeometricRepresentationItem">

    <xs:sequence>

     <xs:element name="Location" type="ifc:IfcCartesianPoint" nillable="true"/>

    </xs:sequence>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcPlacement

 ABSTRACT SUPERTYPE OF(ONEOF(IfcAxis1Placement, IfcAxis2Placement2D, IfcAxis2Placement3D))

 SUBTYPE OF (IfcGeometricRepresentationItem);

  Location : IfcCartesianPoint;

 DERIVE

  Dim : IfcDimensionCount := Location.Dim;

END_ENTITY;

 EXPRESS-G diagram