David Crossley wrote:
> Brian M Dube wrote:
> > 
> > There will always be one more place in the DTD to add this
> > support.
> 
> Yes, that worried me too when the initial XInclude
> was added to the DTD.
> http://issues.apache.org/jira/browse/FOR-1032
> 
> > I found a very old discussion [1] about processing XInclude
> > before validation. This makes a lot of sense and the solution would
> > still be useful after a move to XHTML2. Does anyone remember any
> > efforts to add a preprocessor? and the outcome?
> > 
> > [1] http://marc.info/?l=forrest-dev&m=104124992407064&w=2
> Subject: [RT] Entities in XML docs
> 
> As usual there were other things that needed to be in place first.
> 
> One of those was the ability to do validation in the
> Cocoon pipelines. At the moment we do xml validation
> using Ant before the Forrest/Cocoon engine starts.
> 
> Using Cocoon Validation Transformers
> http://forrest.apache.org/howto-dev.html#debug-validation
> 
> Also Jing and Trang have a new lease of life.
> http://code.google.com/p/jing-trang/
> 
> How is tool support these days for "RELAX NG"?
> 
> I note that George of oxygenxml.com is contributing
> to the Jing-Trang project.

In the past i had tried to get some of this working.
After your message, i resurrected that and managed to
get a bit further. See:

FOR-1172 - enable validation of the internal xml

FOR-1173 - add demonstration of using xml source documents
without declaring a DTD

While rummaging around i also found a relevant old issue:
FOR-101 - Move to RelaxNG (with auto generated DTDs for editors)

Still need to get XInclude processing done a bit earlier
in the sitemaps.

-David