<element name=“ab:addressBook” xmlns:ab=“www.example.com/addressBook

                             xmlns:a="http://www.example.com/address"
       xmlns="http://relaxng.org/ns/structure/1.0">
<zeroOrMore>
  <element name="ab:card">
    <element name="a:name">
      <text/>
    </element>
    <element name="a:email">
      <text/>
    </element>
  </element>
</zeroOrMore>

</element>