Re: Page break navigation

Hi Wilco,

> The success criterion as written, on the one hand is far broader than textbooks.

Indeed, we’ve focused on textbooks as an obvious example but it should apply more widely. The core is that if you take the (non-trivial) trouble to identify the page numbering in the markup, there should be a mechanism to navigate to them. Another scenario would be book clubs for literature.


> As a result, this success criterion is going to require organizations to add page navigation to documents that do not benefit from it in any way.

I’ve asked the EPUB folks about this specifically, and it just isn’t a remotely likely scenario. Adding in the locators is not trivial. Matt said: “it often takes some export fiddling or having an outsourcer insert them”.



> At the other end, the success criterion is so narrowly defined that it does not apply to other formats with which text books may be published.  As a result, WCAG 2.2 doesn't actually add a new guarantee that textbook navigation has actually become more accessible. Only if you're accessing your textbook as an EPUB, through a web viewer may you actually see a benefit from this success criterion.

We did try defining it by types of content at one stage, but the lines are too blurry. You would end up requiring work from organisations when it isn’t needed, e.g. when there isn’t a version in a different format.


> This success criterion does not do what it says on the tin; make navigating multi-page documents accessible. It only applies to EPUB, and only EPUBs that have their page breaks done in a very specific way. It can easily be circumvented.

I don’t think the SC is claiming to make navigating all multi-page documents accessible, particularly in the SC text, it is more specific.

The “specific way” of doing page breaks is following the EPUB3 spec, which seems to be an appropriate anchor point.

> And it relies on the assumption that there will never be any other way to indicate page breaks even in EPUB (like adopting CSS break-before / break-after).

As discussed previously, CSS break-before/after are not suitable for this use-case. They adapt to the content so would result in different page numbers between users.

Also, on the later point about technology specificness: In general it does apply to things like PDF, but for PDF (and EPUB through an EPUB reader) the user-agents provide the mechanism. The problem case is HTML through a browser, where the user-agents do not to that, and there is no indication they ever will so the author is the only role that can solve the problem. (If browsers change, the SC would be fulfilled without author effort.)

Kind regards,

-Alastair

--

@alastc / www.nomensa.com<http://www.nomensa.com>