#### 8.4.3.4 IfcGeometricRepresentationItem

| Item de représentation géométrique
| Geometrische Repräsentation - Element

An IfcGeometricRepresentationItem is the common supertype of all geometric items used within a representation. It is positioned within a geometric coordinate system, directly or indirectly through intervening items.

> NOTE Definition according to ISO/CD 10303-42:1992
> An geometric representation item is a representation item that has the additional meaning of having geometric position or orientation or both. This meaning is present by virtue of:

> - being a Cartesian point or a direction
> - referencing directly a Cartesian point or direction
> - referencing indirectly a Cartesian point or direction

> An indirect reference to a Cartesian point or direction means that a given geometric item references the Cartesian point or direction through one or more intervening geometry or topology items.

> > EXAMPLE 1 Consider a circle. It gains its geometric position and orientation by virtue of a reference to axis2_placement (IfcAxis2Placement) that is turn references a cartesian_point (IfcCartesianPoint) and several directions (IfcDirection).

> > EXAMPLE 2 Consider a manifold brep. A manifold_solid_brep (IfcManifoldSolidBrep) is a geometric_representation_item (IfcGeometricRepresentationItem) that through several layers of topological_representation_item's (IfcTopologicalRepresentationItem) references poly loops (IfcPolyLoop). Through additional intervening entities poly loops reference cartesian_point's (IfcCartesianPoint).

> NOTE Entity adapted from geometric_representation_item defined in ISO 10303-42.

> HISTORY New entity in IFC1.5

XSD Specification:

<xs:element name="IfcGeometricRepresentationItem" type="ifc:IfcGeometricRepresentationItem" abstract="true" substitutionGroup="ifc:IfcRepresentationItem" nillable="true"/>
<xs:complexType name="IfcGeometricRepresentationItem" abstract="true">
<xs:complexContent>
<xs:extension base="ifc:IfcRepresentationItem"/>
</xs:complexContent>
</xs:complexType>

EXPRESS Specification:

ENTITY IfcGeometricRepresentationItem

| ABSTRACT SUPERTYPE OF(ONEOF(IfcDirection, IfcPlacement, IfcPoint))

| SUBTYPE OF (IfcRepresentationItem);

END_ENTITY;

Inheritance Graph:

ENTITY IfcGeometricRepresentationItem

| ENTITY IfcRepresentationItem

| INVERSE

| ENTITY IfcGeometricRepresentationItem

END_ENTITY;

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