[BCP83]    Best Current Practice 83,
              <https://www.rfc-editor.org/info/bcp83>.
              At the time of writing, this BCP comprises the following:

              Rose, M., "A Practice for Revoking Posting Rights to IETF
              Mailing Lists", BCP 83, RFC 3683, DOI 10.17487/RFC3683,
              March 2004, <https://www.rfc-editor.org/info/rfc3683>.