Currently, the documentation at http://dlang.org/spec/ddoc.html has
D_CODE = <pre class="d_code">$0</pre>
However, the compiler actually uses the following:
D_CODE =
<section class="code_listing">
<div class="code_sample">
<div class="dlang">
<ol class="code_lines">
<li><code class="code">$0</code></li>
</ol>
</div>
</div>
</section>
I'm not aware of other differences.