The IfcAxis2PlacementLinear provides location and orientation to place items in a three-dimensional space confined to the context of a curve. Relative placement axes (Axis and RefDirection) are relative to the curve used for linear referencing provided in IfcPlacement Location (IfcPointByDistanceExpression BasisCurve), maintaining the relationship to the tangent of the curve.
The exact direction of the local Z Axis.
The direction used to determine the direction of the local X Axis. In case both Axis and RefDirection are set and not perpendicular an adjustment is necessary to maintain orthogonality to the Axis direction. If RefDirection is omitted, the direction is taken from the curve tangent at Location.
The Location on parent type IfcPlacement shall be of type IfcPointByDistanceExpression
The Axis and RefDirection shall not be parallel or anti-parallel.