WebAIM - Web Accessibility In Mind

E-mail List Archives

Re: making footnotes accessible in PDF documents


From: Duff Johnson
Date: May 27, 2012 10:04PM

On May 26, 2012, at 5:45 PM, Jennifer Sutton wrote:

> Ryan et al:
> Thanks for your time and thoughts, Ryan.

Yes, seconded. The software is constantly under development, and we always appreciate input.

> Writing "a good chunk of Javascript" is not a solution that's going
> to work for my client.
> I suppose the "reading order" could be set to assure that relevant
> footnotes read after each paragraph to which they pertain, but I
> don't believe that's the preferred convention.

Actually, it is preferred - and you'd use the tags tree to set this correctly.

> And I would not be
> keen to somehow set the screen reader reading order to be different
> from the visual reading order (if that's even possible).

It's not only possible, it's desirable. Consider: if you decided to tag the footnote into the correct logical location in the document then a typical "top to bottom, left to right" "visual reading order" for the page would all of a sudden be NOT appropriate in that instance, right?

…yet another reason to help understand why in PDF, tags are determinative of correct "logical reading order" regardless of any other "view".

> Honestly, this kind of footnote navigation is common on the Web and
> has been possible in ebooks for many years, now, so I'd think it'd be
> common in Adobe, since it's more and more being used to create ebooks
> which are likely to have footnotes at the bottom of each page.

Links do indeed suffer unfortunate limitations in PDF at this time. PDF 2.0 (currently under development) will provide a technical basis for links that work directly with the logical structure of the document.

> It seems that I should clarify that the PDF in question already
> exists, so it will not be a matter of converting from Word.

Well, that's important information - it means you are not going to be able to leverage the footnote structure in Word to create a properly tagged PDF. The only solution right now is to edit the tags in the PDF using Acrobat and/or the CommonLook PDF plug in for Acrobat.

> This
> document is large, so it would be a waste of time to convert back to
> Word and recreate.
> I doubt that my client is going to want to procure a separate
> software package to assist with remediation (sorry, Duff).

Everyone is feeling sorry for me! ;-)

> What my client wants to do is to be able to generate PDF documents
> properly (using Adobe's tools), and at the moment, what's in question
> is how to implement footnotes.

The ideal way to implement footnotes in Acrobat alone given the current state of PDF technology is to tag each footnote immediately following the footnote's reference in the body text. This may be accomplished in the tags panel of Adobe Acrobat readily enough, or of course also in the dedicated CommonLook PDF UI (hey, I'm not the one who started talking about our products on this thread! ;-)

> In case this is clearer than what I originally wrote, what I'd like
> to know, specifically, is:
> -- Is it possible to link a footnote at the bottom of a page with its
> corresponding text (in the document body) so as to give the user the
> choice to navigate between the two?

As discussed above, while it's possible today to perform the association via the tags tree, the linking solution will only become possible with PDF 2.0 (ISO 32000-2) which is still a ways off. :-(

> -- If this kind of linked navigation is not possible, and I do want
> the notes at the bottom of the page (which is what the convention in
> the industry of my client is), what's the next best practice?

I'm not sure what you mean by "at the bottom of the page". This is a physical, not a logical location. Yes, the footnotes COULD be tagged to appear at the end of a the page's content - but what if the bottom of the page content is one half of a sentence that continues on the next page? Why would you want the footnotes to interrupt the reading of that paragraph and out of place in the document?

Few take advantage of it, but the correct thing to do with the current version of PDF is this: Tag the footnote with a Note tag. Tag the reference with a Reference tag. Place the Note tag immediately following the Reference tag in the tag tree. Don't mess with the content order panel in Acrobat - you're likely to screw up the page. Plain content-order software can't be expected to do any better than top-to-bottom, left-to-right anyhow.

> I suppose one could bookmark one's place, read the note, and then
> return to reading the body text via the bookmark, but that seems like
> a work-around.

The sad reality is that in today's tech, links in PDF 1.7 can't be used to target a structure element :-(.

Better to tag the PDF correctly and thereby ensure that footnotes are clearly associated with their references.

> If you read the Accessify Forum post I initially cited, you'll see
> that there are conflicting opinions about how this is to be done, and
> my hope is that, since 2008, Adobe may have made this easier.
> As I suggested earlier, I'd really love to see a PDF document in
> which footnotes are implemented in the best way that Adobe tools,
> alone, permit.
> Thanks, and I regret that this seems to require so much explanation.
> I hoped it'd be fairly simple.

Hopefully this is clearer now?

Best regards,

Duff Johnson

President, NetCentric US (creators of CommonLook)
ISO 32000 Intl. Project Co-Leader, US Chair
ISO 14289 US Chair
PDF Association Vice-Chair

Office: +1 617 401 8140
Mobile: +1 617 283 4226