Versioning information (was: Re: Doctypes and the dialects of HTML 5)

Dan Connolly schreef:
> The Web Architecture document suggests that it does belong there:
>
>   "A data format specification SHOULD provide for version information."
>   -- http://www.w3.org/TR/webarch/#ext-version
>
> But I don't see enough supporting argument there to convince me, in
> this case, let alone for me to try to convince
> you (and Lachlan Hunt, and ...) with it.
>
> So I'm taking this up with the TAG:
> should CSS, HTML, etc. documents bear version information?
> http://lists.w3.org/Archives/Public/www-tag/2007Mar/0042.html
>
> See also
>   http://www.w3.org/2001/tag/issues.html#XMLVersioning-41

First of all, I don't think you can consider CSS a data format. 
Therefore, it would not fall within the TAG definition. HTML, maybe, 
although a very human-oriented one, and usually more presentation- than 
data-oriented. But in the end I think whether or not to include 
versioning information is not a general rule but rather based on a 
design decision in the language. Both have their merits.

Finally, in most XML-based formats, the XML namespace provides 
sufficient means for versioning, and no additional version information 
should be provided. Backwards-compatibility breaking changes should 
change the namespace. It serves the purpose, and that is all the 
versioning information needs to do.

Adding a version="1.0", "2.0" attribute is relatively pointless. In 
fact, it will make it harder to implement, because instead of tying in 
different processing models to different namespaces, you then have to 
tie two different processing models into one namespace, and decide which 
to use based on an attribute. That is a much tighter coupling that is 
undesirable. Different incompatible versions of a language should be 
considered equal to different languages, albeit ones that resemble 
eachother.


~Grauw

-- 
Ushiko-san! Kimi wa doushite, Ushiko-san nan da!!
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Laurens Holst, student, university of Utrecht, the Netherlands.
Website: www.grauw.nl. Backbase employee; www.backbase.com.