Q: DTD versioning

Simon St.Laurent simonstl at simonstl.com
Sat Sep 19 14:24:08 BST 1998

At 01:22 AM 9/19/98 +0200, Hans Carlsson wrote:
>Is it possible to have versions of XML DTDs? I'm wondering about the
>'simple' issue of versioning for XML DTD's... How is this being
>addressed by the XML spec (community), tools to be developed etc.?

You might want to take a look at XSchema's XSchema element - we used a
#FIXED Version attribute in the DTD to identify that all documents using
this DTD are using version 1.0 of XSchema.  When we develop another
version, we can create a new DTD and update the value to 1.1 or 2.0 or
something else more interesting.  (Schemas created using XSchema will need
to implement their own versioning mechanism, possibly using this same
technique in their root element.)

It's only guaranteed to work in a validating environment (where we can
count on the parser to read in the external DTD and apply the value), but
it's pretty convenient. (The XML spec only provides for XML's own version
functionality.)  Hope it helps!

Simon St.Laurent
Dynamic HTML: A Primer / XML: A Primer
Cookies / Sharing Bandwidth (November)
Building XML Applications (December)

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