 class="special">&gt;</span><span class="special">&gt;</span> <span class="special">{</span>
  <span class="comment">// types</span>
  <span class="keyword">typedef</span> <a class="link" href="../units/unary_plus_typeof_helper.html" title="Struct template unary_plus_typeof_helper">boost::units::unary_plus_typeof_helper</a><span class="special">&lt;</span> <a class="link" href="../units/quantity.html" title="Class template quantity">boost::units::quantity</a><span class="special">&lt;</span> <span class="id