<billing.information person.href='person.1.xml'> 
  <credit.card id='c1' type='visa' number='5678567856785678' expires.on='20030130'> 
    <name>Sam Smith</name> 
    <us.address object.id='object:account4:0012'> 
      <street>10 Mars Terrace</street> 
      <city>Seattle</city> 
      <state>WA</state>
      <zip main='98060' sub='9000'/> 
    </us.address> 
  </credit.card> 
</billing.information>