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Re: ISSUE-30 (Longdesc) Change Proposal

From: Charles McCathieNevile <chaals@opera.com>
Date: Thu, 17 Dec 2009 18:19:39 +0100
Cc: "public-html@w3.org" <public-html@w3.org>
To: "Maciej Stachowiak" <mjs@apple.com>
Message-ID: <op.u43ee1lowxe0ny@widsith.local>
On Tue, 08 Dec 2009 20:39:11 +0100, Maciej Stachowiak <mjs@apple.com>

> Thanks for providing a Change Proposal for this issue! The chairs are  
> reviewing Change Proposals to ensure that they meet the required  
> structure. Here is our feedback on this Change Proposal:
> (1) This Change Proposal lacks a clearly marked Summary section (perhaps  
> some of the introductory text is a summary, but that is not clear).
> (2) This Change Proposal lacks a clearly marked Details section, and  
> does not provide sufficient detail to identify a specific change. It's  
> mentioned that many sections may change, but does not identify  
> explicitly which changes are required by the Change Proposal.
> (3) This Change Proposal lacks an Impact section.

> On Oct 26, 2009, at 10:53 AM, Charles McCathieNevile wrote:
>> Hello,

>> I would like to propose that the longdesc attribute from HTML 4 be  
>> retained in HTML 5 as an allowed attribute on images.

>> This implies the following changes to the spec:

[I assume these are reasonably clear, and provide sufficient information
for the editor to incorporate the relevant changes into his workflow. Is
that assumption valid, and if not, can you please clarify what I should be

>> at

Section 4.8.2

>> http://dev.w3.org/html5/spec/text-level-semantics.html#the-img-element  
>> img would also become interactive content with longdesc present.

i.e. add "or longdesc" after "usemap" in the phrase "If the element has a
usemap attribute" under the 'Categories' item.

>> The longdesc attribute would be listed as an attribute for the element.

i.e. Add "longdesc" to the list of content attributes, and
"attribute DOMString longdesc;" to the attributes listed in the DOM
Interface for the img element.

>> The attribute is described already in HTML 4 [1] and the description  
>> can be re-used although it should be made clear that the URI to which  
>> longdesc refers can be a relative reference to some part of the same  
>> page (in order to be explicit about which content is associated with  
>> the image), or a different page.

I.e. in the first sentence at [1], add text such as "which may refer to a  
point within the current page or to a different page" after the work  

>> The example, which references an image but appears to provide useless  
>> alt text should not be copied from HTML 4.
>> Other sections that may change:
>>,, should all mention that a longdesc  
>> *may* be provided to provide a detailed *description* of the image,  
>> e.g. to help a person who cannot see it to find it from a description.
>> should mention it as a way to make the association between an  
>> image and the relevant text explicit.
>> should mention it as the preferred way to point to a  
>> description of the image if this is desired, rather than mis-using the  
>> alt attribute for this purpose.
>> should mention that where an image is a key part of the  
>> content, it should have sufficient text in the alt attribute to replace  
>> the image, and using the longdesc attribute for critical information is  
>> a mistake. However, it can be used for additional information if  
>> desired.
>> This has been a controversial topic. It is clear that longdesc is  
>> relevant only to a fraction of images on the Web, and that it is only  
>> provided in a few of the cases where it is actually relevant. It is  
>> also clearly subject to bogus values to a large extent (perhaps the  
>> majority of the time). And its use is relatively limited, even by those  
>> who might be expected to appreciate it.
>> However, it has been implemented multiple times successfully. The fact  
>> that there is bad data associated might account for low overall usage,  
>> but has relatively little impact on implementations, which can readily  
>> choose to simply ignore values which are not URIs, or even to present  
>> the value to the user, and relatively little impact on the user, who  
>> can still benefit from a *good* usage.
>> This would require conformance checking to accept the attribute as  
>> valid, and would imply maintaining the existing requirement on  
>> Authoring Tools[2] to allow the author to use this functionality. It  
>> would maintain conformance of HTML-4 tools and content, rather than the  
>> current expected change leaving them non-conforming.

This has no impact on existing HTML-4 browsers, many of which fail to make
longdesc accessible other than via the DOM. Failure to make this change
will have an impact on assistive technologies such as screen readers,
which use the longdesc attribute to find descriptions of images.

>> [1]  
>> http://www.w3.org/TR/REC-html40/struct/objects.html#adef-longdesc-IMG
>> [2] http://www.w3.org/TR/ATAG-10/ makes several relevant requiremnts
>> cheers
>> Chaals
>> --Charles McCathieNevile  Opera Software, Standards Group
>>    je parle français -- hablo español -- jeg lærer norsk
>> http://my.opera.com/chaals       Try Opera: http://www.opera.com

Charles McCathieNevile  Opera Software, Standards Group
       je parle français -- hablo español -- jeg lærer norsk
http://my.opera.com/chaals       Try Opera: http://www.opera.com
Received on Thursday, 17 December 2009 17:20:35 UTC

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