<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <xsd:complexType name="Address">
    <xsd:sequence>
      <xsd:element name="name"   type="xsd:string"/>
      <xsd:element name="street" type="xsd:string"/>
      <xsd:element name="city"   type="xsd:string"/>
    </xsd:sequence>
  </xsd:complexType>

  <xsd:complexType name="USAddress">
    <xsd:complexContent>
      <xsd:extension base="Address">
        <xsd:sequence>
          <xsd:element name="state" type="USState"/>
          <xsd:element name="zip"   type="xsd:positiveInteger"/>
        </xsd:sequence>
        <xsd:attribute name="country" type="xsd:NMTOKEN" fixed="US"/>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>

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

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

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

  <!-- simple type definition for UKPostcode -->
  <!-- *** pyxb mod: provide missing STD *** -->
  <xsd:simpleType name="UKPostcode">
    <xsd:restriction base="xsd:string">
      <xsd:pattern value="[A-Z]{2}\d\s\d[A-Z]{2}"/>
    </xsd:restriction>
  </xsd:simpleType>

</xsd:schema>