sample.xml

<?xml version="1.0" encoding="utf-8"?>
<!--open the DOCTYPE declaration -
  the open square bracket indicates an internal DTD-->
<!DOCTYPE foo [
<!--define the internal DTD-->
  <!ELEMENT foo (#PCDATA)>
<!--close the DOCTYPE declaration-->
]>
<products xmlns="http://www.xmlplease.com/ns1" xmlns:xp="http://www.xmlplease.com/ns2">
<?style – oh, try /style.css?>
<!--comment -->
   <product xp:id="p1"/>
  <product/>
   <product>
    My text
   </product>
  <!--open the DOCTYPE declaration -
  the open square bracket indicates an internal DTD-->
   <product>
    My text <![CDATA[<><><><>]]>
   </product>
  <![CDATA[<><><><>]]>
</products>