[BCP201]   Best Current Practice 201,
              <https://www.rfc-editor.org/info/bcp201>.
              At the time of writing, this BCP comprises the following:

              Housley, R., "Guidelines for Cryptographic Algorithm
              Agility and Selecting Mandatory-to-Implement Algorithms",
              BCP 201, RFC 7696, DOI 10.17487/RFC7696, November 2015,
              <https://www.rfc-editor.org/info/rfc7696>.