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RE: Liaison with CSS WG to provide a mechanism for expressing the style of document semantics

From: Justin James <j_james@mindspring.com>
Date: Tue, 3 Jun 2008 11:02:25 -0400
To: "'Robert J Burns'" <rob@robburns.com>
Cc: "'HTML Issue Tracking WG'" <public-html@w3.org>
Message-ID: <031701c8c58a$d55c16c0$80144440$@com>

Robert -

I am formally admitting that I do not understand this now. :)

I think maybe I should explain what I think this proposal is saying. Please
let me know if I have this all wrong, in which case it is safe to ignore
most of my comments here!

* Many elements, most notably images, but possibly video or audio as other
obvious cases, have a need for explanatory text.
* This explanatory text is a form of "meta data" to the element, and however
it is marked up needs to let the UA know to handle it as explanatory text.
For example, a screen reader might use a different voice pitch and/or volume
to indicate that the text is an "aside".
* This text is supposed to be used for... I have no idea, to be honest, what
this text is used for that @alt doesn't address. But assuming that it has a
purpose other than what we specify @alt for...
* This text gets defined in CSS, and well as rules for how the browser
should handle its display.

For example (I am totally guessing on the property usage here, this is for
demonstration purposes only):

.pollack {
   legend: "The works of Jackson Pollack";
   legend-presentation: "deep voice, red text";
}

This would cause an element with a class of "pollack" to be displayed (on a
screen-based UA) with the text "The works of Jackson Pollack" somewhere, and
that text should be red; a screen reader would use a "deep voice" when
speaking the words, "The works of Jackson Pollack".

I actually like this proposal to an extent (assuming that it works the way I
think it does). What I like about it is the ability to give hints to the UA
as to the presentation of this additional "helper text". My objection is in
the inclusion of the "help text" in the CSS definition. If you moved the
"legend" property to be an HTML attribute, we would be golden in my book.
For example, if you remove the "legend" property from my previous fake
definition, and used this tag:

<img src="/images/jpollack1.jpg" height="100" width="100" id="pollack1"
class="pollack" alt="Jackson Pollack's most famous painting" legend="The
works of Jackson Pollack" />

What you would get is the usual @alt text, some sort of display of the
legend text "The works of Jackson Pollack" presented in red text and/or a
"deep voice", and the image itself.

And this to me makes sense. Not everything properly has @alt, but @legend
could/should be applied to all elements (data tables spring to mind, for
example). But the major hang up I have here is the inclusion of the legend
text in the CSS. I know that it may save someone some time in the edge case
of someone writing static HTML by hand and using things with the same legend
text more than a few times. Tough for them, they probably need to use a
dynamic app anyways. And it may save some bytes on the wire, to which I say,
"turn on HTTP compression." But in terms of the static semantic goals of
HTML/CSS, putting legend text in CSS is not a good idea from where I sit.

Assuming, of course, that I am thinking of this correctly. :)

J.Ja

-----Original Message-----
From: public-html-request@w3.org [mailto:public-html-request@w3.org] On
Behalf Of Robert J Burns
Sent: Monday, June 02, 2008 7:56 AM
To: Justin James
Cc: 'HTML Issue Tracking WG'
Subject: Re: Liaison with CSS WG to provide a mechanism for expressing the
style of document semantics


HI Justin,

On Jun 1, 2008, at 7:09 PM, Justin James wrote:

>
> Robert -
>
> I do not currently have any questions about the proposal, but I am  
> beginning
> to suspect that I do not understand its purpose. If I have an unclear
> understanding of it, then I have either read it so wrong that I  
> think I
> understand it, or it does not convey its purpose properly.

I'm pretty sure you don't understand it. But I'd like to work on it  
through email and the wiki page to see what I can do so others don't  
have the same misreading.

> I will say this, the more I read this proposal, the more it looks  
> like an
> attempt to compensate for the lack of granularity of @alt, or  
> provide an
> alternative to @alt.

No, it has nothing to do with @alt.

>
>
> Let me rephrase my thoughts, sans examples which are clearly making  
> my point
> not clear.
>
> Content does not belong in a stylesheet (or any kind of style  
> definition).
> "Legend" is content. It does not belong in a style definition. The  
> use case
> provided on the wiki does not make a strong argument for this  
> solution to
> the problem, and the example you cite below (repetitive items  
> require the
> same legend) is not realistic; anyone generating that much repetitive
> content is not writing static HTML by hand, and making new ways of  
> cutting
> down the document size of HTML is not one of our goals as far as I  
> know
> (that's why there is HTTP level compression).

Part of the confusion here is over what is content? Yes, this proposal  
can be thought of as involving content in a sense (after all it uses  
the CSS content property). However, I don't think it is content in the  
sense you're reading it. I think that is contributing to us talking  
past one another.

Keep in mind this is about bridging the semantics of the HTML document  
with the presentation of the CSS document. So the proposed "legend"  
property might be construed as semantic content (in some sense, but  
not in the sense I think you're thinking of it). While on the other  
hand, the "legend-presentation" property involves non-semantic  
content: instead it describes the visual aural or tactile presentation  
declarations.

The use of such presentations legends is necessarily repetitive.  
Consider the extreme example of a default UA stylesheet.

@media screen {
strong {
                 legend: "strong emphasis";
                 legend-presentation: "italic";
                	font-style: italic;
}
}

@media speech {
strong {
                 legend: "strong emphasis";
                 legend-presentation: "increased stress and richness";
	        pitch: medium;
                 pitch-range: 60;
                 stress: 90;
                 richness: 90
}

}

This legend would be used millions or billions of times across pages  
around the World. This legend would be used on pages, many of which  
are hand-coded. Authors of HTML documents could also add their own CSS  
content property usage to include the print media legend in a printed  
document. Or fine-tune this in other ways. The point is that this is  
the type of content that is ripe for reuse, and is already widely  
reused (at least the CSS declarations are reused without legends).

Also to contrast things a bit, the following CSS declaration would  
certainly not include a legend:

body {
	font-family: Georgia, "Times New Roman", Times, serif;
}

In this case the CSS is purely presentations. It conveys no meaning to  
the user that the body uses a serif font.

I hope this helps clarify things. Perhaps this dialog will help make  
it clearer for others.

Take care,
Rob
Received on Tuesday, 3 June 2008 15:15:41 UTC

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