XML/XML Schema/IDREF

IDREF type attribute

   <source lang="xml">

File: Data.xml <?xml version="1.0" standalone="yes"?> <statement

xmlns="http://www.wbex.ru/statement"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.wbex.ru/statement Schema.xsd">
          
  <customer name="name 1" number="CUST123" type="VIP"/>
  <orders count="2">
     <order number="ORD100" owner="CUST123" total="500.00"/>
     <order number="ORD101" owner="CUST123" total="150.00"/>
  </orders>

</statement> File: Schema.xsd <?xml version="1.0" ?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"

 targetNamespace="http://www.wbex.ru/statement"
 xmlns="http://www.wbex.ru/statement">
 <xs:element name="statement">
   <xs:complexType>
     <xs:sequence>
       <xs:element ref="customer" />
       <xs:element ref="orders" />
     </xs:sequence>
   </xs:complexType>
 </xs:element>
 <xs:element name="customer">
   <xs:complexType>
     <xs:sequence />
     <xs:attribute name="number" type="xs:ID" />
     <xs:attribute name="name"   type="xs:string" />
     <xs:attribute name="type"   type="xs:string"
      use="optional" default="normal" />
   </xs:complexType>
 </xs:element>
 <xs:element name="orders">
   <xs:complexType>
     <xs:sequence>
       <xs:element ref="order" maxOccurs="unbounded" />
     </xs:sequence>
     <xs:attribute name="count" type="xs:nonNegativeInteger" />
   </xs:complexType>
 </xs:element>
 <xs:element name="order">
   <xs:complexType>
     <xs:sequence>
     </xs:sequence>
     <xs:attribute name="number" type="xs:ID" />
     <xs:attribute name="owner"  type="xs:IDREF" />
     <xs:attribute name="total"  type="xs:decimal" />
   </xs:complexType>
 </xs:element>

</xs:schema>

</source>