EXPRESS-G diagramThe IfcMeasureResource schema specifies units and defined measure types that may be assigned to quantities. The fundamental unit types used in this schema are based on the SI system defined in ISO 1000+A1, 1992, 1998. Units in measurement systems other than SI may be derived using this schema.
The IfcMeasureResource schema is adapted from the ISO/CD 10303-41:1992, Industrial Automation Systems and Integration: Product Data Representation and Exchange Part 41: Integrated generic resources: Fundamentals of product description and support, and its Measure schema. For more information on the definitions as defined in the formal ISO standard please refer to: ISO/IS 10303-41:1994. The formal standard can be obtained through the local publishers of standards in each individual country.
The measure types and units have been heavily expanded from those of
ISO/CD 10303-41, in order to meet particular IAI domain requirements. Also,
adaptions have been made according to the modelling rules of IFC development,
especially not allowing ANDOR subtype constraint. A summary of SI base and
derived units, related enumeration types and values, and defined measure types
can be found below:
Units and Measures
Summary in PDF-format
Some examples of instantiation of the units and measures can be found
from:
Units and
Measures Examples in PDF-format
NOTE: In the definitions of the unit exponents the use of superscript font has been omitted. Therefore, m2 means square metre, m3 means cubic meter, etc.
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