The objectified relationship IfcRelAssociatesClassification handles the assignment of a classification item (items of the select IfcClassificationSelect) to objects occurrences (subtypes of IfcObject) or object types (subtypes of IfcTypeObject). 

The relationship is used to assign a classification item, or a classification system itself to objects. Depending on the type of the RelatingClassification it is either:

• Reference to an classification item within an external classification system
• Reference to the classification system itself

NOTE: The reference to a classification item includes a link to the classification system within which the item is declared. It assigns the meaning of the classification item to the object (occurrence or type). The reference to the classification system provides the information that the object (occurrence or type) is governed by the classification system but no assignment of a particular items has been done yet. 

changes 

• IFC4 changes: Type of the RelatingClassification attribute changed from IfcClassificationNotationSelect to IfcClassificationSelect.