1<?xml version="1.0" encoding="ISO-8859-1"?>
2<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
3
4  <xs:element name="family" type="family_type">
5      <xs:key name="sibling_key">
6        <xs:selector xpath="siblings/sibling"/>
7        <xs:field xpath="@name"/>
8      </xs:key>
9      <xs:keyref name="sibling_key_ref" refer="sibling_key">
10        <xs:selector xpath="sisters/sister"/>
11        <xs:field xpath="@name"/>
12    </xs:keyref>
13  </xs:element>
14    <xs:complexType name="family_type">
15      <xs:sequence>
16        <xs:element name="siblings" type="siblings_type" />
17        <xs:element name="sisters" type="sisters_type"  />
18      </xs:sequence>
19      <xs:attribute name="name" type="xs:string"/>
20    </xs:complexType>
21    <xs:complexType name="siblings_type">
22      <xs:sequence>
23        <xs:element name="sibling" type="sibling_type" minOccurs="0"  
24maxOccurs="unbounded" />
25      </xs:sequence>
26    </xs:complexType>    
27    <xs:complexType name="sisters_type">
28      <xs:sequence>
29        <xs:element name="sister" type="sister_type" minOccurs="0"  
30maxOccurs="unbounded" />
31      </xs:sequence>
32    </xs:complexType>        
33	<xs:complexType name="sibling_type">
34		<xs:attribute name="name" type="xs:string"/>
35	</xs:complexType>
36	<xs:complexType name="sister_type">
37		<xs:attribute name="name" type="xs:string"/>
38	</xs:complexType>    
39</xs:schema>
40