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IfcSIUnit

Definition from 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).

IfcSIUnit covers both standard base SI units, like meter and second, and derived SI units, like Pascal, square meter and cubic meter.

HISTORY This entity has changes after IFC Release 1.5.1.
This entity has changes after IFC Release 2.0.
ISSUE See issue and change log for issues and changes made in IFC Release 2x.

EXPRESS specification:

ENTITY IfcSIUnit
SUBTYPE OF ( IfcNamedUnit);
Prefix  :  OPTIONAL IfcSIPrefix;
Name  :  IfcSIUnitName;
DERIVE
SELF\IfcNamedUnit.Dimensions  :  IfcDimensionalExponents :=  IfcDimensionsForSiUnit (SELF.Name);
END_ENTITY;

Attribute definitions:

Prefix  :  The SI Prefix for defining decimal multiples and submultiples of the unit.
Name  :  The word, or group of words, by which the SI unit is referred to.
Dimensions  :  The dimensional exponents of SI units are derived by function IfcDimensionsForSiUnit.

References (1):

Name Type Referred through Express-G
IfcNamedUnit Entity
Subtype
Diagram 1

Inheritance graph

ENTITY IfcSIUnit;
ENTITY IfcNamedUnit;
UnitType  :  IfcUnitEnum;
ENTITY IfcSIUnit;
Prefix  :  OPTIONAL IfcSIPrefix;
Name  :  IfcSIUnitName;
DERIVE
Dimensions  :  IfcDimensionalExponents :=  IfcDimensionsForSiUnit (SELF.Name);
END_ENTITY;