Collection Service Description
Collection (may share "superclass" with Exhibition) - grouping construct largely for administrative workflow. May require typing or equivalent special handling so that some Collection-based tasks can discover all the collections.
Note that the CollectionObject entity is inherently hierarchical, and so Collection may just be a CollectionObject that is formally marked, and that may have some additional information. Need to clarify if there is anything in the Collection entity that is not covered by CollectionObject capabilities.