#### IfcObjectPlacement

Natural language names

##### Semantic definitions at the entity

Entity definition

Abstract supertype for the special types defining the object coordinate system. The IfcObjectPlacement has to be provided for each product that has a shape representation.

The object placement can be given:

- absolute, i.e. by an axis2 placement, relative to the world coordinate system,
- relative, i.e. by an axis2 placement, relative to the object placement of another product,
- by grid reference, i.e. by the virtual intersection and reference direction given by two axes of a design grid.

In any case the object placement has to unambiguously define the object coordinate system as either two-dimensional axis placement (IfcAxis2Placement2D) or three-dimensional axis placement (IfcAxis2Placement3D). The axis placement may have to be calculated.

Informal proposition

1. No two or more elements (subtypes of IfcProduct) shall share the same instance of IfcObjectPlacement.

> HISTORY New entity in IFC Release 2x.

Attribute definitions

# | Attribute | Type | Cardinality | Description | A
--- | --- | --- | --- | --- | ---
| PlacesObject | IfcProduct @ObjectPlacement | S[1:1] | The IfcObjectPlacement shall be used to provide a placement and an object coordinate system for a single instance of IfcProduct. |
| ReferencedByPlacements | IfcLocalPlacement @PlacementRelTo | S[0:?] | Placements that are given relative to this placement of an object. |

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | A
--- | --- | --- | --- | --- | ---
IfcObjectPlacement
| PlacesObject | IfcProduct @ObjectPlacement | S[1:1] | The IfcObjectPlacement shall be used to provide a placement and an object coordinate system for a single instance of IfcProduct. |
| ReferencedByPlacements | IfcLocalPlacement @PlacementRelTo | S[0:?] | Placements that are given relative to this placement of an object. |

##### Formal representations

XSD Specification
`<xs:element name="IfcObjectPlacement" type="ifc:IfcObjectPlacement" abstract="true" substitutionGroup="ifc:Entity" nillable="true"/>
<xs:complexType name="IfcObjectPlacement" abstract="true">
<xs:complexContent>
<xs:extension base="ifc:Entity"/>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcObjectPlacement
ABSTRACT SUPERTYPE OF(ONEOF(IfcGridPlacement, IfcLocalPlacement));
INVERSE
PlacesObject : SET [1:1] OF IfcProduct FOR ObjectPlacement;
ReferencedByPlacements : SET [0:?] OF IfcLocalPlacement FOR PlacementRelTo;
END_ENTITY;

EXPRESS-G diagram

`

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