[BCP15]    Best Current Practice 15,
              <https://www.rfc-editor.org/info/bcp15>.
              At the time of writing, this BCP comprises the following:

              Alvestrand, H. and P. Jurg, "Deployment of the Internet
              White Pages Service", BCP 15, RFC 2148,
              DOI 10.17487/RFC2148, September 1997,
              <https://www.rfc-editor.org/info/rfc2148>.