<?xml version="1.0" encoding="UTF-8"?>
<xs:schema elementFormDefault="qualified"
           attributeFormDefault="unqualified"
           xmlns:xs="http://www.w3.org/2001/XMLSchema">

       <xs:element name="Root" type="Root"/>
       <xs:complexType name="Root">
               <xs:sequence>
                       <xs:element name="foo" type="FooType" nillable="true"/>
               </xs:sequence>
       </xs:complexType>
       <xs:complexType name="FooType" abstract="true">
               <xs:simpleContent>
                       <xs:extension base="xs:string"/>
               </xs:simpleContent>
       </xs:complexType>
       <xs:complexType name="RestrictedFooType">
                       <xs:simpleContent>
                       <xs:restriction base="FooType">
                               <xs:enumeration value="one"/>
                               <xs:enumeration value="two"/>
                       </xs:restriction>
               </xs:simpleContent>
       </xs:complexType>
</xs:schema>
