<xs:attribute name="class">
    <xs:simpleType>
        <xs:restriction base="xs:token">
            <xs:enumeration value="faq" />
            <xs:enumeration value="journalarticle" />
            <xs:enumeration value="productsheet" />
            <xs:enumeration value="specification" />
            <xs:enumeration value="techreport" />
            <xs:enumeration value="whitepaper" />
        </xs:restriction>
    </xs:simpleType>
</xs:attribute>