Transition from DTD to XML Schema specification

Hello Group:

More than 5 years ago my organisation, the IPTC (www.iptc.org), has 
created first XML document specifications based on DTDs for the purpose of 

exchanging news in a B2B environment. Now we want move the document 
definitions to XML Schemas (to be precise: the "new" XML Schema replicates 

the "old" DTD), and this drives us into a bad situation:

- for the XML Schema we define a default namespace.

- adopters of our document specification set up an XML database and load 
the XML Schema for structure validation.

- then they receive XML documents which are still based on the DTD and 
hence without a namespace.

- the XML DB rejects these XML instances as invalid - and actually this is 

 right.

What are best practices for such a sliding transition from DTD to XML 
Schema validated documents and are there workarounds to allow the import 
of both non-namespaced and namespaced XML instances. Our document 
specifications are used worldwide and there is no way of defining a "day 
X" from that on DTD based instances are abondoned and only XML Schema 
based instances are allowed.

Thanks 

Michael
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Sent by:
Michael Steidl
Managing Director of the IPTC <>
International Press Telecommunications Council
"Information Technology for News"
Visit us on the web at  http://www.iptc.org