Base collection

The superset/subset relation is maintained by the database, i.e. when creating instances in a subset, they are automatically added to the superset and when deleting instances from a superset, they are automatically deleted from all subsets.

By default, base collections are considered as extendable value domains, i.e. new values are added automatically to the base collection. By marking the collection as "no create", you may, however, define a nonextendable base collection, i.e. you can add instances to the collection, only, which already exist in the base collection.

Far base collections are base collections, which are defined in another instance as the derived collection, i.e. usually in another structure. In contrast to near base collections, collections based on a far base collection need an inverse reference, always. When no inverse reference is defined, the superset/subset relation cannot be maintained.

You refer to near base collections by means of a property path that begins with two dots, like company.employees . Property paths for far base collections contain two or more property names separated by dots. The properties in the path must fulfill the following conditions for being able to provide full support for the far base collection:

• each property in the path except the last one must refer to a single reference property

• each property in the path must have an inverse property

• each property in the path should be "owning", "dependent" or "secondary"