#### 8.4.2.1 IfcDimensionCount

The IfcDimensionCount defins the dimensionality of the coordinate space. It is restricted to have the dimensionality of either 1, 2, or 3 for the purpose of this specification.

> NOTE The shape representations assigned to a geometric representation context may include geometric representation items of lower dimensionality, particularly when defining the boundary of planar surfaces as 2D cross sections for the purpose of 3D swept areas.

> NOTE Definition according to ISO/CD 10303-42:1992
> A dimension count is a positive integer used to define the coordinate space dimensionality.

> NOTE Type adapted from dimension_count defined in ISO 10303-42.

> HISTORY New Type in IFC1.5

XSD Specification:

<xs:simpleType name="IfcDimensionCount">
<xs:restriction base="xs:long"/>
</xs:simpleType>
<xs:element name="IfcDimensionCount-wrapper" nillable="true">
<xs:complexType>
<xs:simpleContent>
<xs:extension base="ifc:IfcDimensionCount">
<xs:attributeGroup ref="ifc:instanceAttributes"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:element>

EXPRESS Specification:

TYPE IfcDimensionCount = INTEGER;
| WHERE
WR1 | : | { 0 < SELF <= 3 } |
END_TYPE;

Formal Propositions:

WR1 | : | The dimension count should be an integer between 1 and 3 NOTE: This is a further constraint by IFC, the upper limit does not exist in STEP.

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