PDF accessibility reading order (reprise)

26th April 2020 | by Ted Page

Once again, I wish I didn’t have to keep making this argument but…

This week yet another article was published making the case that if a PDF is standards compliant (specifically PDF/UA and ISO 32000), by definition it will be accessible. The principal argument of the article was that in a PDF, reading order is determined by the order of the tags, and the order of the tags only.

It cannot be stressed enough that this is an opinion, not a fact.

Try telling, for example, a young person with dyslexia struggling with an exam paper (on which his or her life chances might depend) “I’m sorry if you can’t use the document, but it’s compliant with the standards, so it’s not my problem”.

The fact is that the tags in a PDF, for some assistive technology users, have absolutely no bearing whatsoever on the reading order of text, including text contained within infographics, charts or other diagrams, which can be all over the place to the extent of being unusable. Such problems will have to be fixed in Acrobat’s Content panel, or better still, at source. They have nothing whatsoever to do with a PDF’s tags.

This is just one example. There are plenty of other potential accessibility problems within PDFs that are not addressed at all by the standards, with colour blindness perhaps being the main one.

According to the RNIB, in 2013 there were an estimated 1.93 million people living with sight loss in the UK. With respect to PDF accessibility, the needs of this group will be met at least tolerably well by compliance with standards. But compare this with around 6 million people with dyslexia, and around 3 million people with colour blindness whose needs may not be at all well served by standards-compliant PDFs.

One day the gap between standards compliance and accessibility may be eliminated, but that day may still be a long way off. In the meantime, you have two options with respect to evaluating the accessibility of a PDF:

  • compliance with standards, or
  • compliance with standards and fixing additional problems not addressed by the standards so that your documents will work for the greatest numbers of people.

I know which option I would go for.

How about you?

While you’re here

If you attend one of our PDF accessibility courses you will learn how to test against standards and to go further by testing PDFs with a range of assistive technologies (not just screen readers). In our opinion (there’s that word again), you will need both in order to be confident that the documents you produce will be as accessible as possible.