[BCP215]   Best Current Practice 215,
              <https://www.rfc-editor.org/info/bcp215>.
              At the time of writing, this BCP comprises the following:

              Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.