<element name=“addressBook” ns=“www.example.com

       xmlns="http://relaxng.org/ns/structure/1.0">
<zeroOrMore>
  <element name="card">
    <element name="name">
      <text/>
    </element>
    <element name="email">
      <text/>
    </element>
  </element>
</zeroOrMore>

</element>