Why Doesn't IE5 use the DTD to Validate?

It doesn't appear that IE5 (March 18th release) uses the DTD to validate
XML, as did the IE5 Beta 2 release. Has anyone been able to make IE5 detect
when a doc doesn't follow the rules of the DTD that it references? I've
tried local and public cases. See:

http://members.home.com/kensall/tests/
http://members.home.com/kensall/tests/collection1pubbugs.xml
http://members.home.com/kensall/tests/collection1.dtd

There are three errors that _should_ be detected in collection1pubbugs.xml
with respect to the collection1.dtd: 

   1.The Value element is not defined in the DTD. 
   2.The attribute "Publisher" within the Published element should be
"publisher", as per the DTD. 
   3.Although Notes is a valid element for a Book, it is not valid for a CD,
according to the DTD. 

Am I missing something? Is there some buried option that I have to enable to
get IE5 to consult my DTD? I've confirmed that it is _looking_ for the right
DTD; when I change the DOCTYPE line so that the reference is a non-existent
file, IE5 does complain.

Any help would be greatly appreciated. I'm trying to complete this example
for my next article for WDVL (below).

- Ken Sall                           ksall@xxxxxxx, kensall@xxxxxxxx,
ken@xxxxxxxx
- Century Computing Division         http://www.cen.com/
- AppNet, Inc.                       http://www.appnet.net/
- XML at Web Developers Virtual Lib
http://WDVL.com/Authoring/Languages/XML/
- NG-HTML: Next Generation HTML      http://www.cen.com/ng-html/
- MW3: Motif on the World Wide Web   http://www.cen.com/mw3/


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