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

Re: unifying alternate content across embedded content element types

From: Robert Burns <rob@robburns.com>
Date: Sat, 14 Jul 2007 14:35:01 -0500
Message-Id: <CDF74B30-35F8-4607-940F-E2016A1A5E21@robburns.com>
Cc: public-html@w3.org, Andrew Sidwell <takkaria@gmail.com>
To: Gregory J.Rosmaita <oedipus@hicom.net>


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

>
> robert burns wrote, quote:
>> As an example, think of an <img> that has a @longdesc attached
>> to it.  According to current recommendations, the @alt attribute
>> is still  required. Its not that we require @alt or @longdesc.
>> Rather we  require @alt even if there is a @longdesc value. Is
>> that simply an  oversight? Or have these attributes evolved to
>> serve distinct  purposes: distinct purposes worth using for
>> other embedded content [WINDOWS-1252?]  for other element types?
> unquote
>
> @alt and @longdesc provide distinct purposes:
>
> [...]
>
> so, yes, ALT and LONGDESC serve 2 distinct purposes; alt needs
> to be required in order to avoid perceptual black holes; however,
> i wouldn't feel bound to provide a longdesc for the conformance
> logo, as its meaning is "this page is valid -- go ahead, check
> for yourself" -- of course, on the pages that the validity icons
> are archived, each MUST have a longdesc describing the icon, so
> that the page author can make an informed decision about which
> icon to use...
>
> 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...

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.

In contrast to longdes (or an embedded content elements contents):

> 1. alt text enables the user who -- for whatever reason -- cannot
> process images (text-only browser, for example); often the alt
> text is not an exact duplication of the graphic (say a mailbox)
> but a description of what the iconic link will do when activated
> (in the case of the mailbox example, i would never encourage
> anyone to use alt="mailbox" but rather, alt="Send Email to Webmaster"

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. Adding @alt to embedded content elements would  
degrade (semi-)gracefully in that authors could repeat the  
information at the beginning of the full equivalent (on <object>)  
until target browser HTML5 conformance had reached an acceptable  
level. The other embedded content elements are all new creations of  
HTML5 (or recent UA innovations), so graceful degradation is not as  
much of a concern (as for <object>). For <embed> it may be a problem,  
but <embed> is in desperate need of fixing if anyway (especially if  
we add it to the author conformance criteria).

For UAs, adding @alt to the other elements would be fairly straight  
forward in terms of simply matching the behavior of other elements to  
the <img> behavior.


[1]<http://lists.w3.org/Archives/Public/public-html/2007Jul/0387.html>
[2]<http://esw.w3.org/topic/HTML/LongdescRetention#head- 
ef01c5377a967ead313aeecea431de086517670a>
Received on Saturday, 14 July 2007 19:35:16 UTC

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