[BCP203]   Best Current Practice 203,
              <https://www.rfc-editor.org/info/bcp203>.
              At the time of writing, this BCP comprises the following:

              Leiba, B., "Changing the Registration Policy for the
              NETCONF Capability URNs Registry", BCP 203, RFC 7803,
              DOI 10.17487/RFC7803, February 2016,
              <https://www.rfc-editor.org/info/rfc7803>.