The IfcSizeSelect provides for the selection between different measure types used for provision of a length measure.

NOTE  global units are defined at the single IfcProject instance, given by UnitsInContext:IfcUnitAssignment, the same units are used for the geometric representation items and for the style definitions.

NOTE  Definition according to ISO/CD 10303-46:1992
The size select is a selection of a specific positive length measure.

NOTE  Type adapted from size_select defined in ISO10303-46.

HISTORY  New select type in IFC2x2.

IFC2x3 CHANGE  The SELECT item IfcMeasureWithUnit has been removed from the IfcSizeSelect, the IfcRatioMeasure and IfcDescriptiveMeasure have been added.