8.12.2.21 IfcSizeSelect

The IfcSizeSelect provides for the selection between different measure types used for provision of a length measure.

NOTE  global units are defined at the single IfcProject instance, given by UnitsInContext:IfcUnitAssignment, the same units are used for the geometric representation items and for the style definitions.
NOTE  Definition according to ISO/CD 10303-46:1992
The size select is a selection of a specific positive length measure.
NOTE  Type adapted from size_select defined in ISO10303-46.
HISTORY  New select type in IFC2x2.
IFC2x3 CHANGE  The SELECT item IfcMeasureWithUnit has been removed from the IfcSizeSelect, the IfcRatioMeasure and IfcDescriptiveMeasure have been added.

XSD Specification:

 <xs:group name="IfcSizeSelect">
  <xs:choice>
   <xs:element ref="ifc:IfcDescriptiveMeasure-wrapper"/>
   <xs:element ref="ifc:IfcLengthMeasure-wrapper"/>
   <xs:element ref="ifc:IfcNormalisedRatioMeasure-wrapper"/>
   <xs:element ref="ifc:IfcPositiveLengthMeasure-wrapper"/>
   <xs:element ref="ifc:IfcPositiveRatioMeasure-wrapper"/>
   <xs:element ref="ifc:IfcRatioMeasure-wrapper"/>
  </xs:choice>
 </xs:group>

EXPRESS Specification:

TYPE IfcSizeSelect = SELECT (
IfcRatioMeasure,
IfcLengthMeasure,
IfcDescriptiveMeasure,
IfcPositiveLengthMeasure,
IfcNormalisedRatioMeasure,
IfcPositiveRatioMeasure);
END_TYPE;

Link to EXPRESS-G diagram EXPRESS-G diagram

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