#### IfcRepresentation

Natural language names

##### Semantic definitions at the entity

Entity definition

Definition from ISO/CD 10303-43:1992: A representation is one or more representation items that are related in a specified representation context as the representation of some concept.

The IfcRepresentation defines the general concept of representing product properties.

> NOTE The definition of this entity relates to the STEP entity representation. Please refer to ISO/IS 10303-43:1994 for the final definition of the formal standard.

> HISTORY New entity in IFC Release 2.0
> IFC2x Edition 3 NOTE Users should not instantiate the entity IfcRepresentation from IFC2x Edition 3 onwards. It will be changed into an ABSTRACT supertype in future releases of IFC.
> IFC2x Edition 3 CHANGE The inverse attributes LayerAssignments and RepresentationMap have been added with upward compatibility.

Attribute definitions

# | Attribute | Type | Cardinality | Description | A
--- | --- | --- | --- | --- | ---
1 | ContextOfItems | IfcRepresentationContext | [1:1] | Definition of the representation context for which the different subtypes of representation are valid. | X
2 | RepresentationIdentifier | IfcLabel | [0:1] | The optional identifier of the representation as used within a project. | X
3 | RepresentationType | IfcLabel | [0:1] | The description of the type of a representation context. The representation type defines the type of geometry or topology used for representing the product representation. More information is given at the subtypes IfcShapeRepresentation and IfcTopologyRepresentation. The supported values for context type are to be specified by implementers agreements. | X
4 | Items | IfcRepresentationItem | S[1:?] | Set of geometric representation items that are defined for this representation. | X
| RepresentationMap | IfcRepresentationMap @MappedRepresentation | S[0:1] | Use of the representation within an IfcRepresentationMap. If used, this IfcRepresentation may be assigned to many representations as one of its Items using an IfcMappedItem. Using IfcRepresentationMap is the way to share one representation (often of type IfcShapeRepresentation) by many products. |
| OfProductRepresentation | IfcProductRepresentation @Representations | S[0:1] | Reference to the product shape, for which it is the shape representation. |

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | A
--- | --- | --- | --- | --- | ---
IfcRepresentation
1 | ContextOfItems | IfcRepresentationContext | [1:1] | Definition of the representation context for which the different subtypes of representation are valid. | X
2 | RepresentationIdentifier | IfcLabel | [0:1] | The optional identifier of the representation as used within a project. | X
3 | RepresentationType | IfcLabel | [0:1] | The description of the type of a representation context. The representation type defines the type of geometry or topology used for representing the product representation. More information is given at the subtypes IfcShapeRepresentation and IfcTopologyRepresentation. The supported values for context type are to be specified by implementers agreements. | X
4 | Items | IfcRepresentationItem | S[1:?] | Set of geometric representation items that are defined for this representation. | X
| RepresentationMap | IfcRepresentationMap @MappedRepresentation | S[0:1] | Use of the representation within an IfcRepresentationMap. If used, this IfcRepresentation may be assigned to many representations as one of its Items using an IfcMappedItem. Using IfcRepresentationMap is the way to share one representation (often of type IfcShapeRepresentation) by many products. |
| OfProductRepresentation | IfcProductRepresentation @Representations | S[0:1] | Reference to the product shape, for which it is the shape representation. |

##### Formal representations

XSD Specification
`<xs:element name="IfcRepresentation" type="ifc:IfcRepresentation" substitutionGroup="ifc:Entity" nillable="true"/>
<xs:complexType name="IfcRepresentation">
<xs:complexContent>
<xs:extension base="ifc:Entity">
<xs:sequence>
<xs:element name="ContextOfItems" type="ifc:IfcRepresentationContext" nillable="true"/>
<xs:element name="Items">
<xs:complexType>
<xs:sequence>
<xs:element ref="ifc:IfcRepresentationItem" maxOccurs="unbounded"/>
</xs:sequence>
<xs:attribute ref="ifc:itemType" fixed="ifc:IfcRepresentationItem"/>
<xs:attribute ref="ifc:cType" fixed="set"/>
<xs:attribute ref="ifc:arraySize" use="optional"/>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="RepresentationIdentifier" type="ifc:IfcLabel" use="optional"/>
<xs:attribute name="RepresentationType" type="ifc:IfcLabel" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcRepresentation
SUPERTYPE OF(IfcShapeModel);
ContextOfItems : IfcRepresentationContext;
RepresentationIdentifier : OPTIONAL IfcLabel;
RepresentationType : OPTIONAL IfcLabel;
Items : SET [1:?] OF IfcRepresentationItem;
INVERSE
RepresentationMap : SET [0:1] OF IfcRepresentationMap FOR MappedRepresentation;
OfProductRepresentation : SET [0:1] OF IfcProductRepresentation FOR Representations;
END_ENTITY;

EXPRESS-G diagram

`

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