## 8.6 IfcMeasureResource

### 8.6.1 Schema Definition

The 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.

EXPRESS-G diagram

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