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<?xml version="1.0" encoding="ISO-8859-1"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="unqualified">

	<xs:element name="foo" type="baseType"/>

	<xs:complexType name="baseType">
		<xs:all>
			<xs:element name="bar" type="derivedType" minOccurs="0"/>
		</xs:all>
		<xs:attribute name="attrA" type="xs:string" use="required"/>
	</xs:complexType>

	<xs:complexType name="derivedType">
		<xs:complexContent>
			<xs:extension base="baseType">
				<xs:attribute name="attrB" type="xs:string" use="required"/>
			</xs:extension>
		</xs:complexContent>
	</xs:complexType>
	
</xs:schema>