Redefining ComplexType

Hi all,

suppose the next:

        <xs:complexType name="A">
            <xs:sequence>
                <xs:element name="a" type="xs:string"/>
                    .........
            </xs:sequence>
        </xs:complexType>

and we want to define some elements X, Y and Z. X, Y and Z only must differ in type of  'a' element. So what i need is to redefine the 'a' element of A type to get 3 news types (i.e. typeX, typeY and typeZ), where the structure and elements of A type will be maintained but the type of 'a' will be changed. Is there any way to get this using some kind of extension or something like that? I know that what i need can be reached defining three types separetely and that only differs on 'a' type but i want to know if there's a more "elegant" solution.

thnx in advance,

Jose Guillen.

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