<xs:complexType name="t_MyReusableUniqueKeysList">
        <xs:sequence>
            <xs:element name="GenericElementOfTheList" type="t_GenericElementOfTheList" minOccurs="1" maxOccurs="unbounded"/>
            <xs:unique name="uniqueCheck">
                    <xs:selector xpath="GenericElementOfTheList"/>
                    <xs:field xpath="GenericElementOfTheList_Key"/>
            </xs:unique>
        </xs:sequence>
</xs:complexType>