The following applies to both _ and * emphasis and strong:
Case:
_text _here_
- Markdown.pl:
<em>text _here</em> - PEG-Markdown:
_text <em>here</em>
Case:
- first
second
- third
Markdown.pl:
<ul>
<li><p>first</p>
<p>second</p>
<ul><li>third</li></ul></li>
</ul>
PEG-Markdown:
<ul>
<li>first</li>
</ul>
<p>second</p>
<pre><code>- third
</code></pre>