<?xml version="1.0"?>
<Document>
   <Frame Url="http://www.w3schools.com/tags/planets.htm">
      <Frame Url="http://www.w3schools.com/tags/venus.htm" />
      <Frame Url="http://www.w3schools.com/tags/sun.htm" />
      <Frame Url="http://www.w3schools.com/tags/mercur.htm" />
   </Frame>
</Document>

Example 2: XML you get when visiting http://www.w3schools.com/tags/planets.htm.