Another error in XHTML schema (xhtml-csismap.xsd), 'shape' attrib ute

If the client-side image map schema xhtml-csismap.xsd [1] is included when
validating an XHTML file using the XHTML 1.1 schema, the attribute group for
the <a> element is redefined to also include a.csim.attlist:

<xs:redefine schemaLocation="../req/core/xhtml-hypertext-1.xsd">
        <xs:attributeGroup name="a.attlist">
                <xs:attributeGroup ref="a.attlist" />
                <xs:attributeGroup ref="a.csim.attlist"/>
        </xs:attributeGroup>
</xs:redefine>

However, a.csim.attlist _requires_ the presence of the shape attribute,
which would seem to me to be incorrect, since not all A elements will have a
shape attribute even though client side image map attributes are allowed:

    <!-- modify anchor attribute definition list -->
    <xs:attributeGroup name="a.csim.attlist">
        <xs:attribute name="shape" type="Text" use="required"
default="rect"/>
        <xs:attribute name="coords" type="Text"/>
    </xs:attributeGroup>
	
Kind regards,

-- Steen Lehmann

References:
[1] :
http://www.w3.org/TR/2001/WD-xhtml-m12n-schema-20011219/schema_module_defs.h
tml#a_smodule_Client-side_Image_Map

/**
 * Steen Lehmann - <mailto:slehmann@silverstream.com>
 * Senior Software Engineer (R&D), SilverStream Software 
 * <http://www.silverstream.com>
 */