<xml>
  <input type="hidden" name="mbox" petal:attributes="value cgi/param 'mbox'" />
  <input type="hidden" name="mbox" petal:attributes='value cgi/param "mbox"' />
  ${cgi/param --t 'foo'}
  ${cgi/param --b 'foo'}
  ${cgi/param --ta 'foo'}
  ${cgi/self_url}
  ${foo/bar/baz --t -hello}
</xml>