<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 ... -->
  </restriction>
 </simpleType>

 <!-- simple type definition for Postcode -->
 <simpleType name="Postcode">
  <restriction base="string">
  </restriction>
 </simpleType>

 <!-- simple type definition for UKPostcode -->
 <simpleType name="UKPostcode">
  <restriction base="ipo:Postcode">
    <pattern value="[A-Z]{2}\d\s\d[A-Z]{2}"/>
  </restriction>
 </simpleType>


</schema>