Versioning DTDs?

Marcus Carr mrc at
Mon Oct 25 01:09:44 BST 1999

Ken Gentle wrote:

> In developing an e-commerce dialog (using XML, of course), we've determined
> that the messages need to be versioned.  Specifically, we'll need to have
> some way of versioning a DTD such that the XML parser can "figure out"
> which version of the DTD to use.
> As the XCatalog stuff (for PUBLIC entities) is not widely supported yet
> (based on my rather naive perspective), simply mapping the PUBLIC ids to
> different DTDs won't work.  Additionally, there is the "change-over
> period":  what if I have messages/documents to process in my "queue" when
> the publicly available DTD changes?  If the structure of the two versions
> of the DTD are incompatible, I've introduced a problem...

I have used OmniMark to manage the dependancies for an SGML dataset by putting APPINFO in the
declaration, fixed attributes in the DTD and attributes representing the current DTD in the
document. I was able to ensure that everything matched before anything was processed except
for the start tag of the DOCTYPE element. Although it was written for an older version of
OmniMark and contains a superset of what you need, if you want it, send me offlist mail.


Marcus Carr                      email:  mrc at
Allette Systems (Australia)      www:
"Everything should be made as simple as possible, but not simpler."
       - Einstein

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