Provide a URL to a document that defines the policy (data management plan) with respect to long term support for persisting the identifier.
Rationale: A persistent identifier ensures that the identifier is only assigned to one resource, and there is no confusion arising from the same identifier being associated with multiple objects. Therefore, it is important that a resource provider indicates what they will do in the event the identifier scheme is changed. Typical policies involve listing the deprecated identifer with the new metadata, as well as allowing users to retrieve that content with the deprecated identifier. There should also be a statement that any assigned identifier won't be reused for another digital object.