[BCP82]    Best Current Practice 82,
              <https://www.rfc-editor.org/info/bcp82>.
              At the time of writing, this BCP comprises the following:

              Narten, T., "Assigning Experimental and Testing Numbers
              Considered Useful", BCP 82, RFC 3692,
              DOI 10.17487/RFC3692, January 2004,
              <https://www.rfc-editor.org/info/rfc3692>.