glossref not possible with classifyMap.dtd

Hi Folks

 

I am trying to classify a couple topics in subject as well as use a glossref.

 

The classifyMap.dtd does not seem to support glossref.  Any reason why this is so.

Shown below is a topicsubject from classifyMap.dtd, however the glossref has to be commented out as it will not validate.

 

<!DOCTYPE map PUBLIC "-//OASIS//DTD DITA Classification Map//EN" "classifyMap.dtd">

...

        <topicref href="/Content/Z_old_Get_voicemail_xi28935.xml" class="- map/topicref ">
            <topicsubject>
                <subjectref keyref="SD_PhoneFeatures"/>
                <subjectref keyref="SD_VoiceMail"/>
            </topicsubject>
        </topicref>
    </topicref>
    <topichead navtitle="Glossary" class="+ map/topicref mapgroup-d/topichead ">
<!--        
        <glossref href="" keys="GE_VoiceMail" linking="none"
            toc="no" print="no" search="no" class="+ map/topicref glossref-d/glossref "/>
-->            
    </topichead>