#### 8.4.2.2 IfcClassificationSelect

The IfcClassificationSelect enables selection of whether a classification reference is to be referenced from an external source, or whether a classification is referenced as such.

> NOTE Generally, it is expected that selection will be by IfcClassificationReference to identify an individual classification notation that classifies an element in the building information model. For example an element, such as IfcTank, might be further classified by assigning an IfcClassificationReference with Identification = "L6814" and a ClassificationSource identifying the appropriate version of Uniclass. IfcClassification should only be selected in circumstances where there could be a need to indicate the classification system that will be used without associating a notation or reference to an individual object. This may occur for higher level objects such as IfcProject, IfcSystem, or similar. For example an IfcStructuralAnalysisModel might be classified to be applicable to a particular version of EuroCode.

> HISTORY New select type in IFC2x

> IFC4 CHANGE Select renamed from IfcClassificationNotationSelect.

XSD Specification:

<xs:group name="IfcClassificationSelect">
<xs:choice>
<xs:element ref="ifc:IfcClassification"/>
<xs:element ref="ifc:IfcClassificationReference"/>
</xs:choice>
</xs:group>

EXPRESS Specification:

TYPE IfcClassificationSelect = SELECT (
| IfcClassification, IfcClassificationReference);
END_TYPE;

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