Note: A classification notation may be developed using various notation facets. A facet is a part of the actual notation but which has a specific meaning. For instance, it may be appropriate to classify an item by owning actor (represented by A=Architect) and by an entry from a classification table such as CI/SfB (represented by 210 for external wall). This gives a classification as A210

HISTORY: New class in IFC Release 1.5. It has changed in IFC Release 2x. Documentation corrections made in IFC 2x Addendum 1

ISSUES: See issue and change log for changes made in IFC Release 2x and IFC Release 2x Addendum 1.

Use Definitions

All classifications of an object that are contained within the IFC model are made through the IfcClassificationNotation class (and not through IfcClassification as was the case up to R2.0). For a given object, the IfcRelAssociatesClassification class (contained within the IfcKernel schema) makes the connection between the IfcObject (abstract superclass, IfcDoor has been taken as an example for instantiation) and the IfcClassificationNotation. IfcObject <-- IfcRelAssociatesClassification --> IfcClassificationNotation. Consider an object that is to be classified with the notation "L6814". In this case, the IfcRelAssociatesClassification has the form:

• #1 IFCOWNERHISTORY (.....); 

• #100 IFCDOOR (.....); 

• #200 IFCCLASSIFICATIONNOTATIONFACET ('L6814'); 

• #300 IFCCLASSIFICATIONNOTATION ((#200)); 

• #400 IFCRELASSOCIATESCLASSIFICATION ('abcdefghijklmnopqrst01',#1,$,$,(#100),#300); 

If the object is to have other notations (e.g. B2186 and Z6793), the IfcClassificationNotation has the form:

• #1 IFCOWNERHISTORY (.....); 

• #100 IFCDOOR (.....); 

• #200 IFCCLASSIFICATIONNOTATIONFACET ('L6814'); 

• #210 IFCCLASSIFICATIONNOTATIONFACET ('B2186'); 

• #220 IFCCLASSIFICATIONNOTATIONFACET ('Z6793'); 

• #300 IFCCLASSIFICATIONNOTATION ((#200,#210,#220)); 

• #400 IFCRELASSOCIATESCLASSIFICATION ('abcdefghijklmnopqrst01',#1,$,$,(#100),#300); 

It is a requirement that a classification notation can only bring together facets from the same classification system or source. Bringing together notation facets from different sources within the same classification notation is not allowed. However, multiple classifications can be applied to a single object through the use of more than one instance of IfcRelAssociatesClassification. In this way it is possible to define multiple classification notations where each notation contains facets from a single source.