Epic editor and docbook customization layer

Hi All,

Arbortext's Epic Editor has a problem with the customization layer we've
added for DocBook 4.2. We've followed Bob Stayton's recommendations for
xinclude by using entities in the doctype declaration of our xml files
rather than by editing the DTD. We've also used the same method to add a
small number of custom elements.

Epic refuses to recognize these customizations, with the result being that
the tool ceases to be a validating editor and therefore becomes pretty
useless.

Arbortext support has said that the tool does not support this kind of
customization and the answer is to modify the DTD. Considering that any
number of other editors do support such a customization layer - XMLSpy and
Exchanger come to mind - this would appear to be an unsupportable position.

Does anyone out there have experience with this?

Regards,

Bruce Covell
Senior Technical Publications Consultant
Cadence Design Systems