W3C home > Mailing lists > Public > public-html@w3.org > July 2007

Re: unifying alternate content across embedded content element types

From: Charles McCathieNevile <chaals@opera.com>
Date: Sun, 15 Jul 2007 16:45:47 +0900
To: "Robert Burns" <rob@robburns.com>, "Gregory J.Rosmaita" <oedipus@hicom.net>
Cc: public-html@w3.org, "Andrew Sidwell" <takkaria@gmail.com>
Message-ID: <op.tvhw6ltxwxe0ny@widsith.local>

On Sun, 15 Jul 2007 04:35:01 +0900, Robert Burns <rob@robburns.com> wrote:

> On Jul 14, 2007, at 10:30 AM, Gregory J. Rosmaita wrote:

>> so, yes, ALT and LONGDESC serve 2 distinct purposes...
>> i do strongly agree with robert burns, however, on the need for
>> making the mechanics of equivalent text uniform across all media
>> types, which would lead not only to a richer user experience, but
>> which lowers the burden on the page author and increases the
>> chances that the exposition of equivalent content will be supported
>> by user agents, in a manner specified by the user...

This would be good, if we were designing from the beginning. Given that it  
is possible to add a link to further information (such as a longdesc) in  
the content provided to an object element or something else with content,  
I think that approach is generally superior than having an alt attribute.

Another approach is that used in SVG, which provides two elements (they  
are called title and desc) - so you can decide with CSS which bits get  
rendered when / how.

> Thank you Gregory. Based on what you're saying here, I think it might  
> make sense then to have an @alt attribute added to the other embedded  
> content elements (i.e., object, video, audio, canvas, and embed). The  
> contents of these elements (as opposed to their linked source/data) most  
> closely matches the role of the longdesc attribute.

Hmmm. I actually think if the content as matching alt, but having a little  
more flexibility. Although you can put in a link to stuff that might be  
useful but might be superfluous (which is what longdesc gives) you don't  
have the defined semantics that you do with longdesc.

> Also, Sander Tekelenburg has proposed[1][2] adding both author and UA  
> conformance critieria to codify the distinction between @longdesc and  
> @alt (e.g., limiting @alt to 50 characters).  This would further raise  
> the need for a consistent treatment of these other embedded media  
> elements.

I am not so strongly concerned that we have to make everything match. The  
perfect clean architecture is what XHTML 2 does - this group is more  
directed at ensuring backwards compatibility (if necessary, at the expense  
of theoretical beauty). alt/longdesc works for img, content works well  
(and if IE fix their object implementation to make it a reasonable way to  
include images you can have it for everything). If I was going to add  
anything to the elements with content I would add longdesc.



   Charles McCathieNevile, Opera Software: Standards Group
   hablo español  -  je parle français  -  jeg lærer norsk
chaals@opera.com    Catch up: Speed Dial   http://opera.com
Received on Sunday, 15 July 2007 07:46:24 UTC

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