cate Requirement Levels">RFC2119</a></cite>] [<cite><a class="bibref" data-link-type="biblio" href="#bib-rfc8174" title="Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words">RFC8174</a></cite>]
          when, and only when, they appear in all capitals, as shown here.
        </p></section>

      <section id="introduction"><div class="header-wrapper"><h2 id="x2-introduction"><bdi class="secno">2. </bdi>Introduction</h2><a class="self-link" href="#introduction" aria-label="Permalink for Section 2."></