W3C home > Mailing lists > Public > www-html@w3.org > January 2000

Re: Why DOCTYPE Declarations for XHTML?

From: Murray Altheim <altheim@eng.sun.com>
Date: Tue, 18 Jan 2000 04:21:11 -0800
Message-ID: <38845AB7.DC4E832F@eng.sun.com>
To: "W. Eliot Kimber" <eliot@isogen.com>
CC: www-html@w3.org
"W. Eliot Kimber" wrote:
> Murray Altheim wrote:
> The pain to which I refer is the pain resulting from the use of a
> facility that only gives the illusion of doing what is really wanted,
> such that things that people think are being said or enforced are not
> being said and are not enforceable.

We are limiting our design to validating (as according to the XML definition
of same) the markup structure of a document instance according to the best
ability of establishing a class of documents named "XHTML". It's what was
in the toolkit.

> > > Why should XHTML require the the feature of SGML that XML correctly
> > > worked so hard to eliminate (DOCTYPE declarations) when the use of it is
> > > not reliable as a way to define types, for all the reasons I've stated
> > > many times?
> >
> > Simple answer: there's not a conformant XML parser alive today that does
> > anything other than use DOCTYPE to declare what document type definition
> > a document conforms to,
> But that's exactly my point: DOCTYPE declarations *do not declare
> types*. I don't know what part of *no* people don't get about this.
Well, perhaps what you are calling a type and what others are calling
a type are different. It's intuitively obvious to many people that a 
set of markup declarations called a DTD and defined in a prose spec
that outlines the semantic intentions of the designer, all called a 
"markup language" or "document type" has some value. No, it's not
perfect and it doesn't guarantee that the content of the document 
conforms to the intention of the designer, nor that the content is
marked up correctly. But it does guarantee that the structure of the
markup itself conforms to the DTD. This is all about intention, and
if both the document type designer and the author see eye-to-eye,
and the tools are written in accordance with that same idea, that
there is some measure of interoperability. 

>                        and as you well know (being to my knowledge part
> > of the reason you left the XML WG), the emperor doesn't like PIs. We've
> > been told repeatedly to avoid use of PIs for anything fundamental.
> I wasn't aware that Tim B-L's aversion was to PIs in general. So what?
> Then take the namespace approach and use an attribute of the document
> element to do the same thing.

To do what? Declare what? With what tool support?
> > Until we have an alternative endorsed by the W3C in a W3C specification we
> > must continue to use the tried and true methods as defined in SGML and XML,
> > ie., the tools we have. We can't even use XLink in our specs until it
> > reaches Recommendation.
> You do have an alternative: a namespace use declaration with a meaning
> defined by the XHTML spec.

And that would make XHTML different from every other XML markup language.

> > I honestly don't know why you're arguing with me about this.
> I'm arguing with you about it because it's important. XHTML will set a
> precedent, an important one, and it would be a tragedy if it sets the
> wrong precedent. Pretending that DOCTYPE declarations have any value for
> defining types is wrong and it shouldn't be done. It seems very clear to
> me.

Well, I'm not stupid, and I've read much of what you've written on the
subject as well as that of others, and I maintain that within the bounds
of our design environment I can't see any reasonable alternatives, unless
XHTML is take off on some entirely new territory, on its own from the
rest of the XML community. I don't see XML Schemas doing this either, 
unless I'm mistaken.
> Just because XML provides the optional feature of DOCTYPE declarations
> doesn't mean that XHTML is obligated to require their use or impart any
> special meaning to their use when there are other was to get what you
> want which are reliable.

Such as? Supported by what tools? Something that given a cold day in 
hell would be accepted by the W3C? If we don't use validation via DTD
we have no acceptable means to establish a document type at all. 
> The SGML and XML standards define a universe in which you can only talk
> about a single document. In that context, DOCTYPE declarations do define
> types, types with exactly one instance. But that's not very useful.

Perhaps you can clarify this for me: I have thousands of valid SGML 
documents that conform to document type definitions, using DOCTYPE
declarations. This is of major value to both myself and the company
I work for. I'm trying very hard to understand your point of view (and
you know I respect your intellect and appreciate your patience), but
the above statement is completely counterintuitive to my experience,
which is that I've seen *great value* in validating my document's markup
structure based on DOCTYPEs and DTDs. And continue to do so with XML.

> It is perhaps the most serious failing of SGML (and by inheritance, XML)
> that it does not provide a markup declaration for binding documents to
> true type definitions. But it doesn't and we have to work around that.
> But pretending that DOCTYPE declarations do something they don't is not
> the right workaround.

I'm not pretending anything. I *am* able to validate the markup structure,
and this does have value to me and my company. Our documents are authored
by intelligent, trained writers who sometimes abuse markup but on the 
whole do a great job in creating content that *is* according to type.
And until something comes along that is acceptable to my company and the
vendors that both support us and we support, that's it.
> I don't want to disrupt y'all's work, I was just responding to the issue
> and the reference my earlier postings--I wanted to support Arjun in his
> arguments because I feel at least as strongly about this now as I did
> two years ago. I won't say any more--I've said everything I can say
> about this as clearly as it's possible for me to say it.

Well, I'm sorry then. I'm not trying to be boneheaded about this but we
either have a religious difference or you're asking me to do something
that is both politically and technically not feasible. Both I and a lot
of other people find XML validation valuable. If adding an AF declaration
to the DTD were all that was needed, I'd be happy to oblige. Since the
beginning of XHTML m12n there's been an empty XHTML module named "XHTML 
1.1 Base Architecture" whose content looks like this:

  <!-- This optional module includes declarations that enable XHTML to be used
       as a base architecture according to the 'Architectural Forms Definition
       Requirements' (Annex A.3, ISO/IEC 10744, 2nd edition). For more information 
       on use of architectural forms, see the HyTime web site at:



  <!-- Architecture Base Declaration -->
  <?IS10744 ArcBase html ?>

  <!-- Architecture Notation Declaration -->

  <!-- TBD... -->

If you look, this is actually included in our current distribution.
The module's public text class is declared as ELEMENTS rather than 
NOTATION, but that's more a measure of ignorance and neglect than 

If filling this module in, adding it to the DTD, and lobbying for a 
prose section describing what it's for would do any good, I've never 
been opposed to this; I'm the one who snuck the damn thing in. And if 
either Arjun or you would be so kind as to assist (ie., that I wouldn't
be out on a limb completely), I'd be happy to lobby for this. Since it's 
somewhat below the W3C radar, they might simply not care so long as they
didn't perceive it to damage the spec. But I honestly can't go in and 
suggest this as an *alternative* to XML validation using DOCTYPE 
declarations and DTDs, which as I've said does hold substantial value for
our audience, to whom architectures are understood as namespaces and some
magic handwaving.


Murray Altheim                                   <mailto:altheim@sonic.net>
Member of Technical Staff, Tools Development & Support
Sun Microsystems, Inc. MS MPK17-102
1601 Willow Rd., Menlo Park, California 94025  <mailto:altheim@eng.sun.com>

   the honey bee is sad and cross and wicked as a weasel
   and when she perches on you boss she leaves a little measle -- archy
Received on Tuesday, 18 January 2000 07:22:57 UTC

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