[STD25]    Internet Standard 25,
              <https://www.rfc-editor.org/info/std25>.
              At the time of writing, this STD comprises the following:

              Postel, J., "Daytime Protocol", STD 25, RFC 867,
              DOI 10.17487/RFC0867, May 1983,
              <https://www.rfc-editor.org/info/rfc867>.