#### IfcBuild2Axes

##### Semantic definitions at the function

Function Definition

Definition from ISO/CD 10303-42:1992: This function returns two orthogonal directions. u[1] is in the direction of ref_direction and u[2] is perpendicular to u[1]. A default value of (1.0,0.0,0.0) is supplied for ref_direction if the input data is incomplete.

> NOTE Corresponding STEP function: build_2axes. Please refer to ISO/IS 10303-42:1994, p.100 for the final definition of the formal standard.
> HISTORY New function in IFC Release 1.5

##### Formal representations

EXPRESS Specification

FUNCTION IfcBuild2Axes
(RefDirection : IfcDirection)
: LIST [2:2] OF IfcDirection;
LOCAL
D : IfcDirection := NVL(IfcNormalise(RefDirection),
IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcDirection([1.0,0.0]));
END_LOCAL;
RETURN([D, IfcOrthogonalComplement(D)]);
END_FUNCTION;

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