<xs:attribute name="pubwork">
    <xs:simpleType>
        <xs:restriction base="xs:token">
            <xs:enumeration value="article" />
            <xs:enumeration value="bbs" />
            <xs:enumeration value="book" />
            <xs:enumeration value="cdrom" />
            <xs:enumeration value="chapter" />
            <xs:enumeration value="dvd" />
            <xs:enumeration value="emailmessage" />
            <xs:enumeration value="gopher" />
            <xs:enumeration value="journal" />
            <xs:enumeration value="manuscript" />
            <xs:enumeration value="newsposting" />
            <xs:enumeration value="part" />
            <xs:enumeration value="refentry" />
            <xs:enumeration value="section" />
            <xs:enumeration value="series" />
            <xs:enumeration value="set" />
            <xs:enumeration value="webpage" />
            <xs:enumeration value="wiki" />
        </xs:restriction>
    </xs:simpleType>
</xs:attribute>