12; Inverts the set of expressions matched by a grammar. When used as a transform,
          <code class="computeroutput">proto::not_&lt;&gt;</code> returns the current expression unchanged.
        </p>
</div>
<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../../pr