This feed does not validate.
<feed xmlns="http://www.w3.org/2005/Atom">
<feed xmlns="http://www.w3.org/2005/Atom">
<feed xmlns="http://www.w3.org/2005/Atom">
<published>2003-06-31T15:51:30-0500</published>
^
</entry>
</entry>
</entry>
</entry>
</entry>
In addition, interoperability with the widest range of feed readers could be improved by implementing the following recommendations.
<feed xmlns="http://www.w3.org/2005/Atom">
</entry>
<!--
Author: Sam Ruby (http://intertwingly.net/) and Mark Pilgrim (http://diveintomark.org/)
Copyright: Copyright (c) 2003 Sam Ruby and Mark Pilgrim
-->
<!--
Description: invalid issued date (bad value for day - this one is harder than the others)
Expect: InvalidRFC3339Date{parent:entry,element:published}
-->
<feed xmlns="http://www.w3.org/2005/Atom">
<entry>
<published>2003-06-31T15:51:30-0500</published>
</entry>
</feed>