How to Version XML Applications

I'm witnessing (and participating in!) a recurring discussion both within 
[1] and without [2] the W3C about how to version XML applications. Some 
like to continue the Major/Minor versioning from older formats; others 
(including myself) like a NS based extensibility and versioning (with an 
option to schema types and extension is you want to do something fancy), 
and others are now proposing hybrids. On this note, XSLT was recently cited 
and I find it's text on this matter to be confusing given a presumption 
that other element types might be added to a REC's existing namespace. 
Could the XSLT editor's shed some light on whether this approach is 
presently being used? (Other others adding elements to the W3C namespace?) 
Also, would the TAG like to make some recommendations on this issue: either 
technical, or recommending this be a work item of an existing WG?

Subject: Re: [RSS-DEV] restructuring Purls to reflect version number?
Date: Wed, 11 Sep 2002 09:48:16 -0400
From: Joseph Reagle <>
To:, Ian Graham <>

On Wednesday 11 September 2002 08:36 am, Ian Graham wrote:
> IMHO, changing the nsURL declares a major change, and by
> implication states that code supporting the old NS does
> not support the new one. That's exactly how things work
> with XSLT -- if you change the nsURI, then existing XSLT
> code is completely broken.
> XSLT examples I've seen use version attributes (or other
> such mechanisms) to trigger alternate processing dependent
> on the attribute value, within the context of a given
> namespace.

I'd be careful about relying upon XSLT as a case of best or even common
practice at the W3C with respect to versioning. In fact, the sentence
"Thus, any XSLT 1.0 processor must be able to process the following
stylesheet without error, although the stylesheet includes elements from
the XSLT namespace that are not defined in this specification:" My
understanding of the present W3C's understanding <smile/> is that the XSLT
Recommendation is the exclusive and complete definition of that namespace.
I'll forward this issue to a few W3C lists and see what kind of response I



Joseph Reagle     E0 D5 B2 05 B6 12 DA 65  BE 4D E3 C1 6A 66 25 4E

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Received on Wednesday, 11 September 2002 09:58:20 UTC