Extending DTDs for Backward Compatibility

[David Megginson]

Rick Jelliffe writes:

 > The first declaration of an entity has precedence.
 > 
 > So you can derive a new DTD by merely declaring the new
 > element types you need in the internal subset, and then
 > defining the appropriate parameter entity.

Absolutely right, but this doesn't solve his other problem -- that
processing software written for the base version of the DTD has to be
able to deal with documents written for the extended version.


All the best,


David

-- 
David Megginson                 ak117 at freenet.carleton.ca
Microstar Software Ltd.         dmeggins at microstar.com
      http://home.sprynet.com/sprynet/dmeggins/

xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev at ic.ac.uk
Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/
To (un)subscribe, mailto:majordomo at ic.ac.uk the following message;
(un)subscribe xml-dev
To subscribe to the digests, mailto:majordomo at ic.ac.uk the following message;
subscribe xml-dev-digest
List coordinator, Henry Rzepa (mailto:rzepa at ic.ac.uk)