1<element name="card" xmlns="http://relaxng.org/ns/structure/1.0">
2  <element name="name">
3    <text/>
4  </element>
5  <element name="email">
6    <text/>
7  </element>
8  <element name="preferredFormat">
9    <choice>
10      <value>html</value>
11      <value>text</value>
12    </choice>
13  </element>
14</element>
15