G</h3>
<p>Define this to enable debugging.</p>
<p>With debugging enabled, special output is generated at key points of the
  parse process, using the standard output operator (<tt><span class="keyword">operator</span><span class="special">&lt;&lt;</span></tt>)
  with <tt>BOOST_SPIRIT_DEBUG_OUT</tt> (default is <tt><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span></tt>,
  see below) as its left operand.</p>
<table width="80%" border="0" align="center">
  <