CL-PDF and accessibility via screen readers

[phmarek]

To be readable by screen readers, PDFs need to include a few tags.

CL-PDF should support these tags; if they could be inserted automatically by a flag in WITH-DOCUMENT or so it would be great.

Thanks!

[mbattyani]

Looks like a useful one. Which tags?

[phmarek]

The PDF Reference has "9.8 Accessibility Support", which lists

• Specifying the natural language used for text in a PDF document [...]
• Providing textual descriptions for images or other items [...]
• Specifying the expansion of abbreviations or acronyms

Then there's "9.8.2 Alternate Descriptions"; here's an excerpt:

For annotation types that normally display text, that text (specified in the Contents entry of the annotation dictionary) is the natural source for vocaliza- tion purposes. For annotation types that do not display text, a Contents entry (PDF 1.4) may optionally be included to specify an alternate description.

And there's an Alt tag as well - and some more details.

Basically, I guess that the language needs to be specified (default per file, and then if different per sentence or paragraph - we might be able to use hyphenation-language for that?); and images (and QR codes and links) may need an &key (or &optional) alt argument.