#data
<foo xml:lang="[]">
  <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
    <rdf:Description>
      <hoge xmlns="http://a/"/>
    </rdf:Description>
  </rdf:RDF>
</foo>
#errors
/foo;unknown namespace element;w
/foo/@lang;langtag:language:syntax;m
/foo/@lang;langtag:language:invalid;m
/foo/RDF/Description/hoge;langtag:language:invalid;m
/foo/RDF/Description/hoge;langtag:language:syntax;m