e></pre></div></div><h2 id="rfc5234"><a href="#rfc5234" class="anchor"></a>RFC 5234</h2><p>Parsers as defined in RFC 5234, Appendix B.1.</p><ul class="at-tags"><li class="see"><span class="at-tag">see</span> <a href="https://tools.ietf.org/html/rfc5234#appendix-B" class="value">https://tools.ietf.org/html/rfc5234#appendix-B</a> </li></ul><div class="odoc-spec"><div class="spec value" id="val-alpha" class="anchored"><a href="#val-alpha" class="anchor"></a><code><span><span class="keyword">val</span> alpha : 