The IfcSIUnit covers both standard base SI units such as meter and second, and derived SI units such as Pascal, square meter and cubic meter.
NOTE Definition according to ISO/CD 10303-41:1992
An SI unit is the fixed quantity used as a standard in terms of which items are measured as defined by ISO 1000 (clause 2).
NOTE Corresponding ISO 10303 name: si_unit, please refer to ISO/IS 10303-41 for the final definition of the formal standard.
HISTORY New entity in IFC1.5.1.
|1||Dimensions||IfcDimensionalExponents||The dimensional exponents of the SI base units by which the named unit is defined.|
|2||UnitType||IfcUnitEnum||The type of the unit.|
|3||Prefix||OPTIONAL IfcSIPrefix||The SI Prefix for defining decimal multiples and submultiples of the unit.|
|4||Name||IfcSIUnitName||The word, or group of words, by which the SI unit is referred to.|
> NOTE Even though the SI system's base unit for mass is kilogram, the IfcSIUnit for mass is gram if no Prefix is asserted.
|1||Dimensions||INVALID||The dimensional exponents of SI units are derived by function IfcDimensionsForSiUnit.|
ENTITY IfcSIUnit SUBTYPE OF (IfcNamedUnit); Prefix : OPTIONAL IfcSIPrefix; Name : IfcSIUnitName; DERIVE SELF\IfcNamedUnit.Dimensions : IfcDimensionalExponents := IfcDimensionsForSiUnit (SELF.Name); END_ENTITY;