W3C home > Mailing lists > Public > public-comments-wcag20@w3.org > October 2008

RE: Image use cases that WCAG doesn't address

From: Gregg Vanderheiden <GV@trace.wisc.edu>
Date: Thu, 30 Oct 2008 12:12:08 -0500
Message-Id: <EA08C561-D8BE-4A5E-9C98-68CE3821DD37@trace.wisc.edu>
To: hsivonen@iki.fi
Cc: public-comments-wcag20@w3.org
Hi Henri,

This is a follow-up to our previous email in response to your comment  
to our public comment list (pasted below).   Per our previous email to  
you, we did not feel it appropriate to make changes to the WCAG 2.0  
guidelines themselves. However, we did add one new technique and feel  
there is room to add more, especially in conjunction with some new  
possibilities that might be built into HTML 5.

Toward this end we thought we would start with some background that  
led up to our current guidelines, and then describe into where we  
stand today and techniques - or at least ideas for techniques - that  
might be considered going forward.

Background

We have been working with users with disabilities on this topic for  
over 10 years now.   We have received volumes of comments on our  
drafts over the years and talked with many users with disabilities and  
Web developers.  Our current draft is based on all of this input.   
Here is a brief synopsis of it.

The "alternate text" approach was first developed to allow non-text  
content (e.g. pictures, applets, audio files etc) that could not  
otherwise be accessed by many people with disabilities to be  
accompanied by text that could be turned into visual, auditory or  
tactile forms to better fit a user's needs.  (As we get better tools,  
it will also allow the content to be translated into sign language,  
symbols or simpler forms of the same language).

The question arises as to when it is important for users to access  
information or functionality that is in non-text content.

Decorative
Some places there clearly isn't any information (e.g a decorative  
scroll in the corner of the page).  In these cases there also seems to  
be agreement that the non-text content should be marked so that it is  
not presented to users who cannot see it.

Redundant
Sometimes the information in the non-text content is also presented  
elsewhere on the page.   In this case, the user of assistive  
technology often detects the non-text content (either because their  
assistive technology exposes it or because there is a reference to the  
non-text content present).   Our Guidelines require that a short  
alternate text be provided identifying the non-text content,  
describing it or telling the user where they can find the longer  
description.  For example   "Sales chart - described at bottom of  
page" or  "Sales chart - described in 2nd paragraph following".     
Some have felt that no alt text was required if there was equivalent  
text on the page.   Others found that it was very confusing when they  
encountered non-text content but did not know whether it contained  
information that was not otherwise in the text of the page.   Others  
had problems when people referred to a diagram on the page, for  
instance, and they did not know that the page contained a diagram or  
what it was about.

However, the success criterion is written in such a way that providing  
alternate text use an ALT attribute is not the only way of meeting  
it.  If there is some other method for associating alternate text with  
the non-text content, then that mechanism could be used.    For  
instance, where an image is included in an anchor element along with  
equivalent link text, the image can be given alt="".    We documented  
another such technique in response to your comment (below).  We would  
be interested in discussing other things that might be included in  
HTML 5 to allow text that describes non-text content (or provides the  
same function) to be programmatically associated with the non-text  
content so that the text on the page can be easily located from the  
non-text content.

Content beyond Author Control
You also raised the question of content that will be added later,  
where the author doesn't have any control of the content and cannot  
add meaningful alternate text.  We recognize this situation and have  
provided a concept called a  "Statement of Partial Conformance".    
This allows authors to be able to make a statement about the page that  
does not include the content they can't control.   They can't claim  
the page conforms, because part of it may not.  But they can state  
that the page would conform if that uncontrolled part is not there.    
We took this approach because we didn't want users to encounter  
conforming pages that still contained  information that was not  
accessible.  On the other hand we wanted a means to recognize pages  
where the authors have made the page as conformant as possible.

If these and our previous comments address your concerns please let us  
know.    If not, we would like to meet with you and discuss them.     
Along with your comments, we would like discuss ways that HTML 5 could  
provide new options for associating text descriptions with non-text  
content so that approaches similar to what you are suggesting might be  
developed that would work for users with disabilities and also give  
authors more and better options.  I know that your working group likes  
to work asynchronously but if we could arrange a meeting with you and  
Mike Smith to explore these issues we think it would be productive.

As we need to move forward with WCAG, could you please email or call  
us this week and let us know if you are OK with the WCAG WG's  
response? If you are satisfied, but would still like to meet later to  
explore the topics above, we would also be interested in that. If you  
are not satisfied, you of course have the option of filing a formal  
objection, but we would need this right away.

We are hoping however that the guidelines as they exist, with the  
support of techniques which can be added at any time (because WCAG  
techniques are non-normative), can provide the flexibility that you  
are looking for.

Thanks

Looking forward to hearing from you.

Gregg Vanderheiden and Loretta Guarino-Reid
WCAG  Co-Chairs


Gregg Vanderheiden
gv@trace.wisc.edu

Loretta Guarino-Reid
lorettaguarino@google.com






Received on Thursday, 30 October 2008 17:13:06 UTC

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