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Re: Are there W3C definitions of presentation and content?

From: Bert Bos <bert@w3.org>
Date: Thu, 22 Sep 2005 20:00:55 +0200
To: www-style@w3.org
Message-Id: <200509222000.55261.bert@w3.org>

On Monday 19 September 2005 16:35, Patrick Lauke wrote:
> > Gavin Kistner
> >
> > But now you're tempting me, because I really would like to be
> > able to
> > use CSS to shove ancillary sidebar content as footnotes and create
> > links to it.
>
> But should this not be behaviour that is taken care of by the user
> agent? We'd need a way to define (in content?) that something is
> ancillary information such as a footnote, but leave it up to the
> browser to decide how best to deal with it based on user preference,
> device capabilities, etc

Indeed. One of the nice things of CSS is that it can be ignored. Search 
engines, for example, can (and do) skip style sheets, because there is 
no content in them. But it would indeed be nice if there were a way to 
insert sidebars, footnotes and other content that you'd like to keep in 
a separate file.

There are few methods already and others are being worked on:

1) You can use the <link> element for links that you want the browser to 
handle in a special way. Some well-known types of links are home, up, 
previous, next, alternate and copyright. The browser makes a menu out 
of these, so they don't take up space in the content. (For years, only 
Lynx understood these links, but now several other browser do, too.)

More link types can be proposed and if they are popular enough and 
sufficiently documented, I'm sure browsers and other software will add 
support for them.

2) The new CDF (Compound Document Format) working group of W3C is 
working on how to embed ("transclude" is the proper word) external 
content in a document. <img> and <object> work fine for images, but if 
you try to use them to include an HTML sidebar, they don't work so 
well. The CDF WG will define how to determine the size of such content, 
how to inherit style sheets and how to make the interaction seamless 
(drag-select text that is partly inside the transcluded object, submit 
a form that is partly inside the object, etc.).

Eventually, <object data="navmenu.html">...</object> (when combined with 
the proper style sheet) should be indistinguishable from copying and 
pasting the contents of navmenu.html into the document, except that it 
is more efficient.

3) XHTML2 will probably have a "role" attribute, which is similar to 
"rel," but not restricted to links. Adding "role" to the <object> 
example above allows you to indicate what the role of that transclusion 
is.

For certain predefined types, the browser could then handle that object 
specially: a "navigation menu" could be bound to a special key, so that 
pressing that key zooms that menu to full screen, wherever you are in 
the document; a "footnote" could be automatically suppressed if the 
screen is too small; also on a small screen, an "illustration" could be 
reduced in size, while a "diagram" is not reduced, but allows 
panning...

The same could be done in HTML with the "class" attribute and the people 
working on "microformats" are trying to create a set of well-known 
class names that might eventually become common enough that software 
can treat them specially.



Bert
-- 
  Bert Bos                                ( W 3 C ) http://www.w3.org/
  http://www.w3.org/people/bos                               W3C/ERCIM
  bert@w3.org                             2004 Rt des Lucioles / BP 93
  +33 (0)4 92 38 76 92            06902 Sophia Antipolis Cedex, France
Received on Thursday, 22 September 2005 18:01:06 GMT

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