CCXML Errors

For the following elements:
    <accept>
    <disconnect>
    <dialogstart>
    <reject>
    <redirect>
 
In the DTD (schema too?), the "conid" attributes are defined as "callid".
 
Also, is it a good idea to define the default value (in the DTD) for this attribute as "_event.callid"?  Not do the events not have "callid" field, but if the "conid" is not specified "_event" is almost certainly going to cause an error during runtime.
 
And last but not least:  While in the above elements, it's "conid", in the telephony events it's "connid".