1<element name="addressBook" xmlns="http://relaxng.org/ns/structure/1.0"> 2 <zeroOrMore> 3 <element name="card"> 4 <element name="name"> 5 <text/> 6 </element> 7 <element name="email"> 8 <text/> 9 </element> 10 <optional> 11 <element name="note"> 12 <externalRef href="inline.rng"/> 13 </element> 14 </optional> 15 </element> 16 </zeroOrMore> 17</element> 18