<xs:attribute name="class">
    <xs:simpleType>
        <xs:restriction base="xs:token">
            <xs:enumeration value="attribute" />
            <xs:enumeration value="attvalue" />
            <xs:enumeration value="element" />
            <xs:enumeration value="emptytag" />
            <xs:enumeration value="endtag" />
            <xs:enumeration value="genentity" />
            <xs:enumeration value="localname" />
            <xs:enumeration value="namespace" />
            <xs:enumeration value="numcharref" />
            <xs:enumeration value="paramentity" />
            <xs:enumeration value="pi" />
            <xs:enumeration value="prefix" />
            <xs:enumeration value="comment" />
            <xs:enumeration value="starttag" />
            <xs:enumeration value="xmlpi" />
        </xs:restriction>
    </xs:simpleType>
</xs:attribute>