When checking out the potential clashes in cases where a repository portal display configuration is tied to the oai-dc datastream, one question that came to mind was the possibility of omitting the http link to an offsite document entirely from the oai-dc. That way, the oai-dc data provider could offer the repository’s metadata page as the dc.identifier without any messy entanglements with assigning a different dc value for a document according to its location (archived in the repository or offsite).
But that option also has significant drawbacks. We have to assume that Service Providers will be able to index and search records from the data provided in the oai-dc. This must inform any Data Provider’s (repository’s) decision about what to include in the oai-dc. And some SPs expect to be able to search full text — which means they will need to know the link to the document itself, whether that is in the dc.identifier or some other value such as the dc.relation.