Document formats, accessibility and productivity

30 November 2018 | Ted Page

My recent conversation with someone at the heart of the UK public sector digital realm ended abruptly when I made the argument that some content types can be more accessible in non-HTML formats than they can be in HTML. Unfortunately, although objectively and demonstrably true, this message is not always well received.


The example I gave on this occasion was that, because the accessibility APIs of web browsers can serve up one, and only one, accessible alternative to a graphics object such as a bar chart or infographic, HTML is a less accessible format for these content types than is PDF. The accessible alternative in this example will typically be an alt text description which, if written appropriately, will be suitable for a screen reader user. However, it will be of little use to, say, someone with dyslexia,  even if their assistive technology could read it (some literacy software solutions do read alt attribute values, some don’t).

Many dyslexic readers will be better served by assistive technology that reads out loud (and preferably also highlights with a background colour) any labels, legends, data values or other text content contained within the chart/infographic. The difference between these two assistive technology behaviours is demonstrated in our video PDF accessibility and the non-tags’ reading order.

In HTML, it’s one or the other

The latter reading experience could, of course, be achieved in an HTML page using SVG, but the point is, in HTML it’s one or the other—you cannot simultaneously have both this approach and alt text written to serve the needs of a screen reader user.

…not so in PDF

But in a PDF (or the source InDesign of Illustrator file), as long as you know how to author content correctly, it’s a snap.

A renewed urgency

Recently, the debate about the relative merits of different document formats has been brought into even sharper focus than usual with the incorporation of the EU Accessibility Directive into UK law. Public sector organisations now have less than 2 years to ensure that all their online PDFs (and other online documents) are accessible.

The urge to ban

Some see the ‘solution’ to this ‘problem’ in banning PDFs from public sector websites altogether. Doing so would be a serious error.

Productivity, productivity, productivity…

One of the principal reasons the UK economy lags behind those of other comparable countries is persistently poor levels of productivity. Because tools such as Adobe InDesign are far more powerful and flexible content creation tools than any web Content Management System, banning the PDFs they generate from public sector websites would be to withhold from document producers the best tools for many content creation jobs that they must deal with in their day to day lives. Denying people the best tools for any given job will, by definition, reduce their productivity.


The real solution is that content producers acquire the skills to author content properly in a variety of formats, according to the needs of the end-user. This is not that difficult to do, but we had better get on with it if we are going to meet the now less than 2-year deadline of the new legislation.