1<element name="addressBook"  xmlns="http://relaxng.org/ns/structure/1.0">
2  <zeroOrMore>
3    <element name="card">
4      <choice>
5        <attribute name="name">
6          <text/>
7        </attribute>
8        <group>
9          <attribute name="givenName">
10            <text/>
11          </attribute>
12          <attribute name="familyName">
13            <text/>
14          </attribute>
15        </group>
16      </choice>
17      <attribute name="email">
18        <text/>
19      </attribute>
20    </element>
21  </zeroOrMore>
22</element>
23