W3C home > Mailing lists > Public > w3c-wai-ig@w3.org > July to September 2014

RE: Call for Implementations: HTML5 Image Description Extension (longdesc)

From: John Foliot <john@foliot.ca>
Date: Wed, 13 Aug 2014 07:14:01 -0700
To: "'Adam Powell'" <adam@adaminfinitum.com>, "'Shawn Henry'" <shawn@w3.org>
Cc: "'WAI Interest Group'" <w3c-wai-ig@w3.org>
Message-ID: <00e201cfb700$d797da50$86c78ef0$@ca>
Adam Powell wrote:
> I'm replying to this working group, rather than the HTML
> Accessibility Task Force list because I have a question
> about what I should do to contribute.
> I am unfamiliar with the phrase 'Call For Implementations."
> It sounds as if we should create webpages that follow the
> draft's details/specifications so that it can be tested but
> I don't recall ever having seen this step before.
> I reviewed the linked pages for guidance but all the mentions
> of "implementation" seem to be guidance for authors and user
> agents.
> Can anyone clarify?

Hi Adam,

Thanks for the question.  Your reading is indeed correct (although here it is 
somewhat skewed by the fact that we already have some implementations of 

You are correct, in that what it means is that it is an invitation to start 
using @longdesc: if you are a content author, and you are adding a complex 
image to your page (say for example a complicated graph or chart, or an 
infographic), then as an author, please go ahead and start using @longdesc, 
knowing that now it is a fully valid and compliant part of HTML5.

If you are a browser vendor, assistive technology manufacturer, or other 
"user-agent" tool maker (this includes authoring tools too, BTW), then from 
that perspective please go ahead and tool/re-tool your application to support 
@longdesc, as once again it is on track to being a full part of HTML5 
(Candidate Recommendation is the final step on the standards journey, before 
becoming a full Recommendation - which is W3C speak for Standard).

The phrase you are tripping up on is the 'Call for Implementations' - this is 
standard language for announcements like this, and is normally applied when 
there is a "new" feature added. It signals the fact that there is already 
emergent support for that new feature: it is a mechanism to try and break the 
'chicken and egg' problem. It is W3C's way of saying go ahead, there is enough 
support today to start using it safely.

In the case of @longdesc, which was an existing attribute in HTML4 that was 
not originally being supported in HTML5, this extension spec corrects that 
problem, by ensuring that @longdesc remains valid when moving from HTML 4 to 
HTML5. Support in most of the mainstream screen readers exists today (JAWS, 
NVDA, WindowEyes, and a number of other non-North American screen readers, the 
exception being VoiceOver), along with any number of browser extensions, which 
extends the usefulness of @longdesc for users with other requirements 
(cognition issues perhaps?) - those plugins are also exposing the @longdesc 
content to the end-user.

The single largest "problem" with @longdesc today has always been, well, 
actually 2 problems: the chicken and egg problem (authors would not use 
@longdesc, for lack of mainstream browser support; browsers would not support 
due to lack of usage), and poorly crafted / incorrect usage of the @longdesc 
attribute (coupled with the "link-rot" problem of long ago[*]).

Collectively we are seeking to right those wrongs, and your contributions, as 
an author, user-agent implementer (or even consumer - if you consume a 
provided longdesc description - send an email to the author and thank them!) 
will help move this useful attribute forward.

Hope this answers your question, feel free to ping back if anything is 


John Foliot
Web Accessibility Specialist
W3C Invited Expert - Accessibility
Co-Founder, Open Web Camp

[* see: http://john.foliot.ca/wysiwyg_longdesc/ ]
Received on Wednesday, 13 August 2014 14:14:35 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 13 October 2015 16:21:52 UTC