<?xml version="1.0"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
	<xsd:element name="myElem" type="xsd:string">
		<xsd:key name="testref">
			<xsd:selector xpath=".//vehicle"/>
			<xsd:field xpath="@regNo"/>
		</xsd:key>
		<xsd:keyref name="regKeyref" refer="testref">
			<xsd:selector xpath=".//vehicle"/>
			<xsd:field xpath="@regNo"/>
		</xsd:keyref>
	</xsd:element>
</xsd:schema>