Re: [docbook] Alternate text for table and image accessibility - textobject, alt, summary?

[Barton Wright <ordinant@gmail.com>]

Hi Janice,

I’m sorry you’ve encountered conflicting advice about the use of the several DocBook-related mailing lists. Part of the problem is the somewhat nebulous descriptions of each list on the OASIS DocBook Technical Committee’s web page.  They could use much more straightforward language to say something like the following: 

Use the docbook-apps list if you have questions about using DocBook or the DocBook XSL stylesheets. 

The other lists mentioned at the link above are primarily for discussions among implementers of the DocBook XML standard and its next release. The docbook-apps list is also the recommended starting point in Bob Stayton’s indispensable book  The great majority of those of us in the trenches who live and breathe DocBook for a living hang out on the docbook-apps list. It is generally a welcoming place, and we never disparage newbie questions. 

As for your question, the textobject element’s purpose is to provide a text-only backup display in case an image or other media object can’t be found at runtime. In a well-regulated DocBook output system, it just doesn’t happen that your images are not found, but I suppose it might happen in rare cases of a disk read error or some such. So the textobject is orthogonal to any issues of accessibility.

Looking at the the DocBook 5 Definitive Guide’s element reference page for <alt>, I see:

The alt element was originally added to DocBook to provide an alternative, usually text, presentation for graphical elements. In DocBook V5.0, it was made a “ubiquitous” element so that it's available almost everywhere. The semantic intent of alt is simply that it provides alternative text, often for accessibility.

So it looks like <alt> is what you’re looking for, as a child element of a <mediaobject> container for an image, parallel to the <info> element. It also looks like <alt> is valid in DocBook 5 as a child of the <table> element, or at least for CALS tables. (I think you’ll find that all of the tables in your new job are CALS tables.) You’ll have to try using <alt> as a child of <table>, and build your HTML output that way, to see if <alt> provides a genuinely accessible aid for tables.

Looking all through the element reference, I don’t see an element or attribute named summary, so I’m not sure what you meant there.

Best of luck with the new job!

Apologies in advance if this is the wrong list. I've had conflicting advice about what to post to docbook vs. docbook-apps.

I'm brand new to DocBook, and am reviewing the current source files for the doc set at my new job.

Is there a recommendation for providing alternate text for accessibility?

The current source files have textobject for images and nothing for tables.

Is the alt element better than textobject?

For tables, should I use alt or summary?

Thanks,

Janice