div>
<h6>
<a name="spirit.qi.reference.parser_concepts.naryparser.h4"></a>
            <span><a name="spirit.qi.reference.parser_concepts.naryparser.invariants"></a></span><a class="link" href="naryparser.html#spirit.qi.reference.parser_concepts.naryparser.invariants">Invariants</a>
          </h6>
<p>
            For each element, <code class="computeroutput"><span class="identifier">E</span></code>,
            in any NaryParser, <code class="computeroutput"><span class="identifier">P</span></code>,
     