How to put a DTD in the result tree?

I'm using XSL to convert a source XML document into 
a target XML document.

I would like the target XML document to include a DTD.
How can I do this via XSL?

The following is an example of a target XML document that 
contains a DTD:

<?xml version="1.0"?>
<!DOCTYPE Invoice SYSTEM "invoice.dtd">
<Invoice>
    <!-- Other elements... -->
</Invoice>

Thanks.

Bob

------
Bob Lyons
EC Consultant
Unidex Inc.
1-732-975-9877
boblyons@xxxxxxxxxx
http://www.unidex.com/


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