#data
<feed xmlns="http://www.w3.org/2005/Atom">
  <title>aa</title>
  <id>http://hoge/</id>
  <link rel="self" href="aa"/>
  <updated>2011-01-03T00:11:22Z</updated>
</feed>
#is-document
#errors
/;xml:no DTD validation;i

#data
<feed xmlns="http://www.w3.org/2005/Atom">
  <title>aa</title>
  <id>http://hoge/</id>
  <link rel="self" href="aa"/>
  <updated>2011-01-03T00:11:22Z</updated>
  <!---->abc<!---->
</feed>
#errors
/feed/"abc";character not allowed;m

#data
<feed xmlns="http://www.w3.org/2005/Atom">
  <title>aa</title>
  <id>http://hoge/</id>
  <link rel="self" href="aa"/>
  <updated>2011-01-03T00:11:22Z</updated>
  <aa></aa>
</feed>
#errors
/feed/aa;element not defined;m
/feed/aa;element not allowed;m

#data
<feed xmlns="http://www.w3.org/2005/Atom">
  <title>aa</title>
  <id>http://hoge/</id>
  <link rel="self" href="aa"/>
  <updated>2011-01-03T00:11:22Z</updated>
  <in-reply-to xmlns="http://purl.org/syndication/thread/1.0" href="http://s/" ref="http://y/"/>
</feed>
#errors
/feed/in-reply-to;limited use;w
/feed/in-reply-to;element not allowed;m

#data
<feed xmlns="http://www.w3.org/2005/Atom">
  <title>aa</title>
  <id>http://hoge/</id>
  <link rel="self" href="aa"/>
  <updated>2011-01-03T00:11:22Z</updated>
  <hoge xmlns="http://foo/"></hoge>
</feed>
#errors
/feed/hoge;unknown namespace element;u

#data
<feed xmlns="http://www.w3.org/2005/Atom">
  <title>aa</title>
  <id>http://hoge/</id>
  <link rel="self" href="aa"/>
  <updated>2011-01-03T00:11:22Z</updated>
  <hoge xmlns=""></hoge>
</feed>
#errors
/feed/hoge;unknown namespace element;u