Definition from ISO/CD 10303-41:1992: A measure with unit is the specification of a physical quantity
as defined in ISO 31 (clause 2).
IfcMeasureWithUnit has two usages:
1. For representing measure value together with its unit on the entity type attribute level; thus
overriding the IFC model global unit assignments.
2. For conversion based unit to give the conversion rate and its base.
NOTE Corresponding STEP name: measure_with_unit, please refer to ISO/IS 10303-41:1994
for the final definition of the formal standard.
HISTORY New entity in IFC Release 1.5.1.
|| The value of the physical quantity when expressed in the specified units.
|| The unit in which the physical quantity is expressed.