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Re: LONGDESC in HTML5?

for

From: Duff Johnson
Date: Sep 25, 2010 8:36AM


On Sep 25, 2010, at 9:08 AM, Steven Faulkner wrote:
> I cannot disagree more. the content of the alt attribute can be and is many
> things:


First, I'm going to associate myself in general with Steve's remarks - well put, and as such, unarguable.

I want to offer comment on a couple items and offer a point of information from the PDF world to see if it resonates.

> The abscence of content indicates the image is decorative.


In PDF, if we consider that a graphical object is "decorative" and thus, not part of the semantic content, we mark it as "artifact" at which point it (logically) disappears - ie, it won't appear in the DOM, so AT can't "see" it. Problem solved.

> if the image is a photograph, diagram, illustration, cartoon, chart the alt
> may be a short description of the content.


Likewise in PDF. However, PDF adds the possibility of explicitly identifying the content of an image as a representation of text. This is especially handy for ligatures, for example, and obviously, many documents use this sort of thing for section headings.

The question of "replacement" vs. "description" is resolved by one's choosing to use the "Actual Text" attribute of the image's corresponding Figure tag.

In practice, the use of the Actual Text attribute should be interpreted by AT as meaning that there's no actual "image" present (logically) at all, and thus the value of the attribute is to be treated as inline text, without announcing the fact of the image at all.

In all other cases (ie, where we use the alt. text attribute) the valid (we think) processing is to announce the fact of the image, followed by the alt. text.

> +others

Indeed.

In our world, content "is" what the author intends, period. I'd like to hear the "best available" case for eliminating longdesc - I'm unimpressed by what I've heard so far. I can think of number of use-cases in which a short vs. long (for example, literal) description of an image would be a service to the end-user.

PDF has no "longdesc" attribute right now - more's the pity. Perhaps we should put it in for 32000-2? Please let me know what you think - I need to get final comments into the draft very soon!

Duff Johnson
Appligent Document Solutions, CEO
US Committee for ISO/CD 14289 (PDF/UA), Chair
US Committee for ISO 32000 (PDF/Reference), Vice Chair
US Committee for ISO 19005 (PDF/A), Member
PDF/A Competence Center North American Chapter, Chair

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