Howto extend xml schema types

Learned today how to extend XML schema types

<xs:complextype name="Payment">

 <xs:sequence>

    <xs:element name="paymentType" type="PaymentType">

 </xs:element>

</xs:sequence>



<xs:complextype name="CardPayment">

 <xs:complexcontent>

    <xs:extension base="Payment">

    </xs:extension>

 </xs:complexcontent>

</xs:complextype>