The concept Classification Association describes how objects and object types can be further described by associating references to external sources of information. The source of information can be:
a classification system;
a dictionary server;
any external catalogue that classifies the object further;
any service that combines the above features.
An individual item within the external source of information can be selected. It then applies the inherent meaning of the item to the IfcObject or IfcTypeObject.
The main attributes to be provided for a Classification Association are:
Identification: holds the key provided for a specific reference to classification items (or tables)
Name: allows for a human interpretable designation of a classification notation
The following diagram shows the generic classes and relationships used when applying this concept.
In addition, concepts may have particular importance to common or standardised industry practices and scenarios. For these specific usage scenarios, the table below shows a recommended list of general usage patterns that users may adopt.