Problem: We do not know if ISO 19139 can handle describing the relationship of a related link to a resource using a controlled vocabulary (in this case datacite's CV).

Acceptance Criteria:

Research if ISO 19139 can handle describing the relationship of a related link to its resource.
If we can describe the relationship, research how to include a different controlled vocabulary into our ISO 19139 xml.
Identify how to extend ISO to include a schema such as DataCite to describe these relationships related to DigitalTransferOptions and CI_OnlineResource including example.
Document our findings in this ticket.