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