XML dissector / DTDs

Hi,

I've been playing with the XML dissector, adding a new DTD for 
application/reginfo+xml (RFC 3680) as shown below.
It is already useful that I can now filter on the presence of a 
particular field and its value, but I was hoping that I would get some 
indication when frames don't match the DTD description.

I'm using a colouring rule with the filter (xml.tag or xml.attribute or 
xml.doctype) to show frames that have elements not described in the 
schema in an alarming red colour, but can't tell if mandatory elements 
or attributes are missing or something appears too often, etc.... (I did 
try to constrain the values of attributes, e.g. reginfo.state has to be 
"full" or "partial", but this isn't included below as it had no 
effect).  Am I missing something?

Regards,
Martin



<? ethereal:protocol
   proto_name="reginfo"
   description="Reginfo XML doc (RFC 3680)"
   hierarchy="yes" ?>

<!--
   
-->

<!DOCTYPE reginfo
[

<!ATTLIST reginfo xmlns CDATA #REQUIRED
                  version CDATA #REQUIRED
                  state CDATA #REQUIRED>

<!ELEMENT uri (#PCDATA)>

<!ELEMENT display-name (#PCDATA)>
<!ATTLIST display-name  lang CDATA #IMPLIED>

<!ELEMENT unknown-param (#PCDATA)>

<!ELEMENT contact (uri | display-name | unknown-param)* >
<!ATTLIST contact      id CDATA #REQUIRED
                       state CDATA #REQUIRED
                       event CDATA #REQUIRED
                       expires CDATA #IMPLIED
                       retry-after CDATA #IMPLIED
                       duration-registered CDATA #IMPLIED
                       q CDATA #IMPLIED
                       cseq CDATA #IMPLIED
                       callid CDATA #IMPLIED>


<!ELEMENT registration (contact)*>
<!ATTLIST registration aor CDATA #REQUIRED
                       id CDATA #REQUIRED
                       state CDATA #REQUIRED>
]>