1  <?xml version="1.0"?>
 2  <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
 3    <xsd:complexType name="PurchaseOrderType">
 4      <xsd:sequence>
 5        <xsd:all>
 6          <xsd:element name="shipTo" type="USAddress"/>
 7          <xsd:element name="billTo" type="USAddress"/>
 8          <xsd:element name="items" type="Items"/>
 9        </xsd:all>
10        <xsd:sequence>
11          <xsd:element ref="comment" minOccurs="0" maxOccurs="unbounded"/>
12        </xsd:sequence>
13      </xsd:sequence>
14      <xsd:attribute name="orderDate" type="xsd:date"/>
15    </xsd:complexType>
16  </xsd:schema>