<schema targetNamespace="http://www.example.com/IPO" 
        xmlns="http://www.w3.org/2001/XMLSchema" 
        xmlns:ipo="http://www.example.com/IPO">

 <annotation>
   <documentation xml:lang="en">
     Addresses for International Purchase order schema
     Copyright 2000 Example.com. All rights reserved.
   </documentation>
 </annotation>

 <complexType name="Address">
   <sequence>
     <element name="name" type="string"/>
     <element name="street" type="string"/>
     <element name="city" type="string"/>
   </sequence>
 </complexType>

 <complexType name="USAddress">
   <complexContent>
     <extension base="ipo:Address">
       <sequence>
         <element name="state" type="ipo:USState"/>
         <element name="zip" type="positiveInteger"/>
       </sequence>
     </extension>
   </complexContent>
 </complexType>

 <complexType name="UKAddress">
   <complexContent>
     <extension base="ipo:Address">
       <sequence>
         <element name="postcode" type="ipo:UKPostcode"/>
       </sequence>
       <attribute name="exportCode" type="positiveInteger" fixed="1"/>
     </extension>
   </complexContent>
 </complexType>

 <!-- other Address derivations for more countries -->

 <simpleType name="USState">
   <restriction base="string">
     <enumeration value="AK"/>
     <enumeration value="AL"/>
     <enumeration value="AR"/>
     <!-- and so on ... -->
     <enumeration value="PA"/>
   </restriction>
 </simpleType>

 <!-- simple type definition for UKPostcode -->

 <simpleType name="UKPostcode">
    <restriction base="string">
        <pattern value="[A-Z]{1,2}[0-9R][0-9A-Z]? [0-9][A-Z]{2}"/>
    </restriction>
 </simpleType>
</schema>  