#### IfcDirection

Natural language names

##### Semantic definitions at the entity

Entity definition

Definition from ISO/CD 10303-42:1992: This entity defines a general direction vector in two or three dimensional space. The actual magnitudes of the components have no effect upon the direction being defined, only the ratios X:Y:Z or X:Y are significant.

> NOTE: The components of this entity are not normalized. If a unit vector is required it should be normalized before use.

> NOTE: Corresponding STEP entity: direction. Please refer to ISO/IS 10303-42:1994, p.26 for the final definition of the formal standard. The derived attribute Dim has been added (see also note at IfcGeometricRepresentationItem).

> HISTORY: New entity in IFC Release 1.0

Attribute definitions

# | Attribute | Type | Cardinality | Description | A
--- | --- | --- | --- | --- | ---
1 | DirectionRatios | REAL | L[2:3] | The components in the direction of X axis (DirectionRatios[1]), of Y axis (DirectionRatios[2]), and of Z axis (DirectionRatios[3]) | X
| Dim :=HIINDEX(DirectionRatios) | IfcDimensionCount | [1:1] | The space dimensionality of this class, defined by the number of real in the list of DirectionRatios. | X

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | A
--- | --- | --- | --- | --- | ---
IfcRepresentationItem
IfcGeometricRepresentationItem
IfcDirection
1 | DirectionRatios | REAL | L[2:3] | The components in the direction of X axis (DirectionRatios[1]), of Y axis (DirectionRatios[2]), and of Z axis (DirectionRatios[3]) | X
| Dim :=HIINDEX(DirectionRatios) | IfcDimensionCount | [1:1] | The space dimensionality of this class, defined by the number of real in the list of DirectionRatios. | X

##### Formal representations

XSD Specification
`<xs:element name="IfcDirection" type="ifc:IfcDirection" substitutionGroup="ifc:IfcGeometricRepresentationItem" nillable="true"/>
<xs:complexType name="IfcDirection">
<xs:complexContent>
<xs:extension base="ifc:IfcGeometricRepresentationItem">
<xs:attribute name="DirectionRatios" use="optional">
<xs:simpleType>
<xs:restriction>
<xs:simpleType>
<xs:list itemType="xs:double"/>
</xs:simpleType>
<xs:minLength value="2"/>
<xs:maxLength value="3"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
</xs:extension>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcDirection
SUBTYPE OF (IfcGeometricRepresentationItem);
DirectionRatios : LIST [2:3] OF REAL;
DERIVE
Dim : IfcDimensionCount := HIINDEX(DirectionRatios);
END_ENTITY;

EXPRESS-G diagram

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