Global attributes from other namespaces, how to use?

I need to define a complex type called Title, in which I have to use the
global attributes xml:lang and xlink:type from their respective namespaces.
How do I do that?

Is this the proper way? What should I put for the XML namespace?

<xsd:complexType name="Title">
    <xsd:simpleContent>
        <xsd:extension base="xsd:string">
            <!-- Add xml:lang="en-US" global attribute -->
            <xsd:attribute
                    name="lang"
                    namespace="What should I put here for XML1.0?"
                    type="xsd:language"
                    use="default" value="en-US"/>
            <!-- Add xlink:type="title" global attribute -->
            <xsd:attribute
                    name="type"
                    namespace="http://www.w3.org/1999/xlink"
                    type="xsd:string"
                    use="fixed" value="title"/>
        </xsd:extension>
    </xsd:simpleContent>
</xsd:complexType>

Thanks for any help.