W3C home > Mailing lists > Public > w3c-wai-gl@w3.org > October to December 1998

Re: introducing new semantics to HTML

From: Nir Dagan <nir@nirdagan.com>
Date: Wed, 18 Nov 1998 01:08:32 GMT
Message-Id: <199811171557.QAA16716@sahara.upf.es>
To: w3c-wai-gl@w3.org
Al says:

"Where is the contradiction?  CLASS was put in HTML4.0
specifically to be an extension mechanism, to support semantics
not covered in the DTD.  This is just the tip of the iceberg.  In
XML all semantics is after the fact, except for one very abstract
inclusion tree and cross-reference via X-pointer."

Class is an extention mechanism for author defined semantics. 

Class is not a mechanism that allows the W3C to extend HTML
in a way that breaks existing documents.

HTML spec. says authors can define any class for any purpose.

Since the class attribute exists in an experimental HTML version
published by the W3C shortly after CSS1 became 
recommendation, we can safely assume that every class name that 
can you think of has been used by many people for completely 
different author defined semantics.

I may have used class=nav to indicate a poem.

If WAI decides that class=nav is defaulted by 
browsers to {speak:none} it is exactly the same as 
saying that from now on H1 should be defaulted 
by browsers to {display:table}, as getting all my poems 
not to be read is more or less as bad as displaying all 
my headings as tables.

Any class name may have pre defined semantics 
in *existing particular documents*.

Authors who believed the W3C, assumed that browsers 
and users do not and never will set style rules for the author 
defined classes.

On the other hand if we say that the new HTML element 
NAVBAR may be defaulted to display:none in browsers, 
it is a problem of the author if he extended W3C 
recommendations to include this element to describe poems.
This is because HTML states that authors should not 
extend the DTD by declaring new elements.

In regard to XML, its advantage is the you can create 
documents in a "modular" way using some *prespecified* semantics 
of different tag-sets (MathML, vector graphics, etc.), as well 
as some of the author's own, if needed.

The fact that an author can use author defined set of tags without 
any universal meaning is useless because anything you can do with 
XML + stylesheets you can do with HTML + 
stylesheets using only the SPAN element with the class attribute.
(as the SPAN element and class attribute have no 
predefined semantics).

The advantage of XML is not that WAI says 
that I have to rewrite my website because 
the WAI decided that class=nav is a navigation 
bar after I, following HTML4.0,  decided that it 
is poem.

In this sense if WAI says that browsers should safely assume that 
class=nav is a navigation bar, and skip them when spoken, 
WAI recommendations are backward imcompatible with HTML4.0, 
which allows class=nav to be anything that the author wanted, 
including a poem.

Nir Dagan, Ph.D.

"There is nothing quite so practical as a good theory." 
-- A. Einstein
Received on Tuesday, 17 November 1998 11:07:26 UTC

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