Re: Formatting Objects considered harmful

Subject: Re: Formatting Objects considered harmful
From: Håkon Wium Lie <howcome@xxxxxxxxxxxxxxxxx>
Date: Sat, 17 Apr 1999 12:28:20 +0200 (MET DST)
John E. Simpson wrote:

 > Thought-provoking reading. But I can't help wondering if your angst is
 > misplaced.

I hope it is.

 > Your general thesis seems to be that XSL style sheets containing only
 > formatting objects are meaningless (literally devoid of semantics).

I wouldn't call them style sheets any longer. They are documents which
consist only of formatting object. 

 > Although the essay is well-written and cogently argued, the point of
 > "Formatting Objects considered harmful" itself rather falls apart if one
 > rejects the appeal of an FO-only document.

True. If FO-only documents are so unappealing that they will not be
used, there is no danger. Let's list the "unappealing" factors:

 - XFO documents are bigger than the XML/XTL source
 - XFO documents are more device-dependent than the XML/XTL source
 - XFO documents don't contain the semantics of the XML/XTL source

Now, if we replace "XFO" with "PDF" in the statements above, they are
still true. So, is PDF so unappealing that noone wants to use it?
Certainly, the use of PDF on the Web isn't that huge, but I suspect
that's because PDF viewers integrate badly with browsers rather than
authors finding PDF itself unappealing.

So, the question to you becomes: do you think the people who promote
and use PDF on the Web today will find the idea of XFO documents
unappealing?

 > Your analysis of how FOs will limit accessibility hinges on your answer to
 > a "FAQ" which uses the example of why an aural style sheet is a difficult
 > thing to present reliably to clients:
 > 
 >      1.there must be a specification for aural formatting objects 
 >      2.there must be implementations of aural formatting objects 
 >      3.the fact that the user has an aural client must be known to the server 
 >      4.all web sites must install [XSL style sheets containing only 
 >        transformational operations] to transform content into aural 
 >        formatting objects 
 > 
 >      Among these, the first two will require much time and work.
 >      The third is undesirable, while the fourth is impossible in
 >      practice. Besides, caching suffers.
 > 
 > Fair enough, but I don't see how (say) CSS2's aural styling (which answers
 > #1) gets around #2 or 3, and #4 is even *more* impossible since, of course,
 > CSS can't transform squat.

The crucial difference is that in a HTML+CSS or XML+CSS scenario there
is no possibility of writing XFO documents. This means that e.g. aural
User Agents will not be faced with trying to contruct aural renderings
from visual formatting objects.

CSS has a mechanism for users to apply style sheets to documents. I
expect most aural style sheets to be supplied by the user, and step #3
and #4 are therefore not necessary.

#2 is approximately the same for ACSS and aural FOs.

ACSS can do some simple transformations which are useful in aural
environments. For example, it can:

 - add aural "cues" before and after elements
 - turn off the rendering of all but headling elements

 > Deep apologies if I've misread your arguments. As I said, it was
 > thought-provoking reading, which isn't all that easy to come by; I just had
 > to suspend my disbelief in order to let my thoughts be provoked. :)

Your feedback is much appreciated. The FAQ section may have to be
expanded as a result...

-h&kon

Håkon Wium Lie             http://www.operasoftware.com/people/howcome
howcome@xxxxxxxxxxxxxxxxx                      simply a better browser



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