[STD6]     Internet Standard 6,
              <https://www.rfc-editor.org/info/std6>.
              At the time of writing, this STD comprises the following:

              Postel, J., "User Datagram Protocol", STD 6, RFC 768,
              DOI 10.17487/RFC0768, August 1980,
              <https://www.rfc-editor.org/info/rfc768>.