When do I add an ObjectRef to metadata?
As background one must understand the Id/IdRef facility in XML. Within XML Schema, attributes can be declared of type ID or IDREF. An element with an ID-type attribute can be pointed at. The ID is the label. An attribute of type IDREF points to an element containing an ID-type attribute. Each IDREF must have a matching ID to point at within the document. No dangling pointers are allowed. ebXML Registry Schema depends heavily on this Id/IdRef mechanism. An example is a submission containing a RegistryPackage and a Classification. The classification declares the RegistryPackage to be a submission set or folder. The RegistryPackage object has an attribute id of type ID. This tells us it can be pointed to. The Classification object has an attribute classifiedObject of type IDREF. This must point to an object containing a attribute of type ID. Pointing is achieved by having the ID and the IDREF contain the same value. In general, the value of IDREF must match an ID of same value within the
