[XML Schema 1.1] Does mode="none" on a subtype nullify the openness of its parent type?

Hi Folks,

Consider this type which specifies open content:

    <complexType name="Publication" abstract="true">
        <openContent mode="interleave">
            <any />
        </openContent>
        <sequence>
            <element name="Title" type="string" />
            <element name="Author" type="string" />
            <element name="Date" type="gYear"/>
        </sequence>
    </complexType>

And here's a subtype that extends the Publication type. Notice that it also specifies open content, but with mode="none":

    <complexType name="BookPublication">
        <complexContent>
            <extension base="pub:Publication">
                <openContent mode="none">
                    <any />
                </openContent>
                <sequence>
                    <element name="ISBN" type="string"/>
                    <element name="Publisher" type="string"/>
                </sequence>
            </extension>
        </complexContent>
    </complexType>

Does mode="none" mean that extension elements cannot be inserted around the base type's elements as well as the subtype elements? That is, does mode="none" on a subtype nullify the openness of its parent type?

/Roger