<element name=“addressBook” xmlns=“relaxng.org/ns/structure/1.0”>

<zeroOrMore>
  <element name="card">
    <attribute name="name">
      <text/>
    </attribute>
    <attribute name="email">
      <text/>
    </attribute>
    <optional>
      <attribute name="note">
        <text/>
      </attribute>
    </optional>
  </element>
</zeroOrMore>

</element>