<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">
   International Purchase order schema for Example.com
   Copyright 2000 Example.com. All rights reserved.
  </documentation> 
 </annotation>

 <!-- include address constructs -->
 <include
  schemaLocation="address_.xsd"/>

 <element name="purchaseOrder" type="ipo:PurchaseOrderType"/>

 <element name="comment" type="string"/>

 <complexType name="PurchaseOrderType">
  <sequence>
   <element name="shipTo"     type="ipo:Address"/>
   <element name="billTo"     type="ipo:Address"/>
   <element ref="ipo:comment" minOccurs="0"/>
   <element name="items"      type="ipo:Items"/>
  </sequence>
  <attribute name="orderDate" type="date"/>
 </complexType>

 <complexType name="Items">
  <sequence>
   <element name="item" minOccurs="0" maxOccurs="unbounded">
    <complexType>
     <sequence>
      <element name="productName" type="string"/>
      <element name="quantity">
       <simpleType>
        <restriction base="positiveInteger">
         <maxExclusive value="100"/>
        </restriction>
       </simpleType>
      </element>
      <element name="USPrice"    type="decimal"/>
      <element ref="ipo:comment" minOccurs="0"/>
      <element name="shipDate"   type="date" minOccurs="0"/>
     </sequence>
     <attribute name="partNum" type="ipo:SKU" use="required"/>
    </complexType>
   </element>
  </sequence>
 </complexType>

 <simpleType name="SKU">
  <restriction base="string">
   <pattern value="\d{3}-[A-Z]{2}"/>
  </restriction>
 </simpleType>

</schema>