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

<rng:zeroOrMore>
  <rng:element name="card">
    <rng:element name="name">
      <rng:text/>
    </rng:element>
    <rng:element name="email">
      <rng:text/>
    </rng:element>
  </rng:element>
</rng:zeroOrMore>

</rng:element>