[BCP98]    Best Current Practice 98,
              <https://www.rfc-editor.org/info/bcp98>.
              At the time of writing, this BCP comprises the following:

              Camarillo, G., "The Internet Assigned Number Authority
              (IANA) Header Field Parameter Registry for the Session
              Initiation Protocol (SIP)", BCP 98, RFC 3968,
              DOI 10.17487/RFC3968, December 2004,
              <https://www.rfc-editor.org/info/rfc3968>.