[STD26]    Internet Standard 26,
              <https://www.rfc-editor.org/info/std26>.
              At the time of writing, this STD comprises the following:

              Postel, J. and K. Harrenstien, "Time Protocol", STD 26,
              RFC 868, DOI 10.17487/RFC0868, May 1983,
              <https://www.rfc-editor.org/info/rfc868>.