<xs:simpleType name="metadataRoleBaseType">
    <xs:annotation>
        <xs:documentation>orphan simpleType retained in hope it can be used for role</xs:documentation>
    </xs:annotation>
    <xs:restriction base="xs:token">
        <xs:enumeration value="action" />
        <xs:enumeration value="caption" />
        <xs:enumeration value="dialog" />
        <xs:enumeration value="expletive" />
        <xs:enumeration value="kinesic" />
        <xs:enumeration value="lyrics" />
        <xs:enumeration value="music" />
        <xs:enumeration value="narration" />
        <xs:enumeration value="quality" />
        <xs:enumeration value="sound" />
        <xs:enumeration value="source" />
        <xs:enumeration value="suppressed" />
        <xs:enumeration value="reproduction" />
        <xs:enumeration value="thought" />
        <xs:enumeration value="title" />
        <xs:enumeration value="transcription" />
    </xs:restriction>
</xs:simpleType>