<xs:attribute name="HolderType" use="optional">
    <xs:annotation>
        <xs:documentation xml:lang="en">Provides the type of document holder.</xs:documentation>
    </xs:annotation>
    <xs:simpleType>
        <xs:restriction base="xs:NMTOKEN">
            <xs:enumeration value="Infant">
                <xs:annotation>
                    <xs:documentation xml:lang="en">The document holder is an infant.</xs:documentation>
                </xs:annotation>
            </xs:enumeration>
            <xs:enumeration value="HeadOfHousehold">
                <xs:annotation>
                    <xs:documentation xml:lang="en">The document holder is a head of household.</xs:documentation>
                </xs:annotation>
            </xs:enumeration>
        </xs:restriction>
    </xs:simpleType>
</xs:attribute>