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Re: XHTML 2.0 User Agent Conformance

From: <olafBuddenhagen@web.de>
Date: Fri, 31 Oct 2003 16:31:28 +0100
To: www-html@w3.org
Message-ID: <20031031153127.GA579@sky.local>

Hi,

On Fri, Oct 31, 2003 at 11:03:09AM -0000, Jim Ley wrote:

> > I think it would be wise to state in the conformance section of
> > XHTML2 that user agents must process a page as strictly as a general
> > XML document.
> 
> XHTML 1.0 and 1.1 already has this ridiculous assertion AIUI.

The Problem is actually that XHTML 1.0 does *not*. It's allowed to be
served as text/html, in which case this doesn't apply.

As for 1.1, people are also serving this as text/html, which is plain
wrong and really silly. (Actually, what they do is writing XHTML 1.0
with some restrictions to mostly fit the 1.1 spec as well; but as long
as it's served as text/html, it's not really an XHTML 1.1 document.)

> >   ie. displaying an error message if the markup is invalid,
> 
> This is a very bad idea, users do not need to be shown the mechanics,
> they're interested in getting the content.

Wrong, wrong, wrong!

I'm sure this discussion is redundant, as it certainly has been
discussed more than enough by the XML WG when they introduced that
restriction. But I am willing to explain anyways:

The whole and only relevant advantage of using XML is that the user
agent *has to* refuse processing a broken document. Because web authors
and web editor vendors just do not care whether their documents are
valid; when it looks OK in their preferred browser, they just put it
out, and others have to see how they get it displayed... ONLY when every
browser says: "This is broken and I WILL NOT SHOW IT", authors will be
forced to follow specs. Period.

When this requirement is relaxed, everone will be free again to publish
any crap he can come up with, and user agents will have to make
something of it again -- bye bye standards, bye bye interoperability,
bye bye XML.

> User Agents have bugs, if a UA has a bug which leads it to think my
> valid document is invalid and displays error or fails to render the
> document - I've done nothing wrong, and there is nothing I can do to
> fix it, but my clients and customers get a bad impression of me.

XML is quite simple to parse. Bugs pertaining the well-formedness of a
document are not very likely. If some browser actually has bugs here, it
will fail with much more than only your site, and the vendor will have
to do something about it.

Actually the reason for the vicious circle of authors publishing ever
more broken documents and browsers accepting ever more crap, is that
users generally tend to blame "incorrectly" displayed documents on the
browser and not the author breaking standards.

> Also XHTML 1.0 has shown the importance of the flexible rendering to
> allow for user agents and Mark Up Language recommendation writers to
> develop new standards which are compatible with what has gone before -
> XHTML 1.0 can only be rendered by todays UA's because they were fault
> tolerant.  If we remove fault tolerance we lose that ability to
> correct the errors in our ML.

If we really gave up the hope that venders will ever ship browsers
compliant to new standards, I do not see any point in working on XHTML 2
at all.

BTW, Mozilla, Opera, and Konqueror all handle XHTML 1 correctly. Too sad
the vendor having 95% market share doesn't care a damn...

> What happens with an errata which fixes an error in the original XHTML
> 2.0 specification, UA's pre-Errata would handle a document different
> from UA's post-Errata, this would almost certainly not be sustainable.

Browsers generally do not validate, so this is not an issue. The
well-formedness doesn't change, unless XML would be "corrected". (Which
seems quite unlikely at this point...)

> Have you considered the cost of shipping a conformant browser?

This is an important point to mention; an issue that regulary makes me
want to cry. It would really help if the W3C folks would just start to
think twice before shipping unimplementable standards...

Anyways, shipping an unimplementable standard and then allowing people
to implement whatever parts they feel like, is not a viable option. No
point in creating such "standards" at all.

-Olaf-
Received on Friday, 31 October 2003 10:39:25 GMT

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