1<grammar xmlns="http://relaxng.org/ns/structure/1.0"> 2 3 <start> 4 <element name="addressBook"> 5 <zeroOrMore> 6 <element name="card"> 7 <ref name="card.attlist"/> 8 </element> 9 </zeroOrMore> 10 </element> 11 </start> 12 13 <define name="card.attlist"> 14 <group> 15 <attribute name="name"> 16 <text/> 17 </attribute> 18 <attribute name="email"> 19 <text/> 20 </attribute> 21 </group> 22 </define> 23 24</grammar> 25