<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema
	xmlns:xsd="http://www.w3.org/2001/XMLSchema"
	targetNamespace="http://a.b.c"
	xmlns:ns="http://a.b.c"
	elementFormDefault="qualified">

	<xsd:element name="Superset">
		<xsd:complexType>
			<xsd:sequence>

				<xsd:element name="Subset1">
					<xsd:complexType>
						<xsd:sequence>
							<xsd:element name="Type1" maxOccurs="unbounded">
								<xsd:complexType>
									<xsd:attribute name="PrimaryKey"/>
								</xsd:complexType>
							</xsd:element>
						</xsd:sequence>
					</xsd:complexType>
					<xsd:key name="key_Type1">
						<xsd:selector xpath="ns:Type1"/>
						<xsd:field xpath="@PrimaryKey"/>
					</xsd:key>
				</xsd:element>

				<xsd:element name="Subset2">
					<xsd:complexType>
						<xsd:sequence>
							<xsd:element name="Type2" maxOccurs="unbounded">
								<xsd:complexType>
									<xsd:attribute name="ForeignKey"/>
								</xsd:complexType>
							</xsd:element>
						</xsd:sequence>
					</xsd:complexType>
				</xsd:element>

			</xsd:sequence>
		</xsd:complexType>

		<xsd:keyref name="keyref_Type2_Type1" refer="ns:key_Type1">
			<xsd:selector xpath="ns:Subset2/ns:Type2"/>
			<xsd:field xpath="@ForeignKey"/>
		</xsd:keyref>

	</xsd:element>
</xsd:schema>