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

Re: LONGDESC: some current problems and a proposed solution added to the wiki

From: Robert Burns <rob@robburns.com>
Date: Sat, 30 Jun 2007 20:44:58 -0500
Message-Id: <7541A2D8-C937-47C3-B8FC-6F888CBCC354@robburns.com>
Cc: "Philip TAYLOR" <Philip-and-LeKhanh@royal-tunbridge-wells.org>, "HTML WG" <public-html@w3.org>
To: Peter Krantz <peter.krantz@gmail.com>

On Jun 30, 2007, at 5:10 PM, Peter Krantz wrote:

> On 6/30/07, Philip TAYLOR <Philip-and-LeKhanh@royal-tunbridge- 
> wells.org> wrote:
>> Why would you want to display the fallback content
>> at the same time as the image ?  If both are to
>> be presented concurrently, the so-called "fallback"
>> content isn't fallback at all, but simply an intrinsic
>> part of the page (and would, of course, be marked up
>> as such).
> The description of a complex picture may be helpful to people without
> a disability. Why hide it in the fallback content and force editors to
> repeat the content elsewhere? If I make it part of the page, how would
> e.g. a screen reader know that the particular content is connected to
> the image?
> Why not make it possible to use CSS and script to modify the
> presentation of the description. An example could be that the user is
> able to click and slide out the description from underneath the image
> or choose to display it some other way.

I think you're discussing two different issues at the same time. 1)  
How we recommend UAs (especially visual UAs) handle fallback content;  
2) How one should author content that is not fallback content; and 3)  
Whether fallback content is necessary if the author has already said  
everything desired in the main content.

In terms of the first issue: yes, it may be desirable to have UAs  
make fallback content available for viewing alongside the parent  
content or to swap between the two. One use case I could imagine  
would be someone with a visual impairment who is not totally blind.  
Similarly, someone with a cognitive disability may benefit from  
reading textual description of visual and aural media that is  
otherwise difficult to comprehend.

On the second and third issues, an author may include lengthy prose  
about embedded content and then the author may determine she has  
nothing else to say in the fallback content. For example this author  
may note be targeting an audience that requires any further  
descriptive content. The media itself provides everything necessary  
through its own fallback content such as closed captioning. Or as  
I've stated before, we might recommend UAs extract description  
metadata right out of an image and an author determines that metadata  
description is sufficient for the audience's fallback content.. In  
these cases the fallback would be left blank.

The HTML5 recommendation could eventually include some discussion of  
these boundary issues and how authors might or might not require  
fallback content. It also might be useful to provide specific  
guidance to visual UAs on how they might present content with  
fallback content combined or alternate between the two.

Take care,
Received on Sunday, 1 July 2007 01:45:13 UTC

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