[BCP78]    Best Current Practice 78,
              <https://www.rfc-editor.org/info/bcp78>.
              At the time of writing, this BCP comprises the following:

              Bradner, S., Ed. and J. Contreras, Ed., "Rights
              Contributors Provide to the IETF Trust", BCP 78, RFC 5378,
              DOI 10.17487/RFC5378, November 2008,
              <https://www.rfc-editor.org/info/rfc5378>.