[type of data: normalized heading—other entity identifiers]
If a classification identifier has already been created in the catalog for a particular combination of disciplinary point of view and subject, use that identifier for all subsequently acquired works that are about that subject from that disciplinary point of view. If the identifier for a subject from a particular disciplinary point of view changes over time, change each normalized ocurrence of the identifier throughout the catalog.
Variant classification access
Ensure that catalog users doing any type of catalog search can search under any form of name that has been used to denote a particular concept, object, place, event, etc., and be led to the classification numbers being used in the catalog to identify that concept, object, place, event, etc., from all possible disciplinary points of view, so that the user can choose which disciplinary point of view is of interest [type of data: normalized heading—variant identifiers]