Accessible PDFs – Usability and Navigation

woman using a screen reader at her laptop in a sunny office

What you see is NOT what everyone gets

Imagine you are an assistive technology (AT) user and you purchased a new programmable slow cooker.  You need to know how to use it. You can’t read the printed manual because you can’t see it, so you go to the website and find the PDF owner’s manual. It is 20 pages of directions in 4 different languages. How do you find the information you need?  Screen reader users rely on headings, tables of contents, and links to find information in documents.  But those elements must be digitally tagged so the assistive technology can find them.  Without proper digital tags, it could take an hour of reading through this manual just to find how to set the timer.

How AT uses digital tags

What you see isn’t always what an assistive technology user gets. Screen readers and Braille displays convey digital information in PDF documents via “tags.” The tags identify the elements as text, a heading, an image, lists, tables, or links.  The tags then provide whatever information has been coded digitally into that element. 

For example, if your PDF contains an image, the assistive technology can easily convey that this element is an image.  But unless a text alternative (alt-text) has been coded into the image element describing it, the assistive technology user will not know what the image actually shows.  So if the image is a chart of, say, a pie chart of preferred ice cream flavors, the AT would read “image” but not tell the end-user that the image is a chart unless alt text is included.

How AT users move through documents

One of the largest issues with PDFs for assistive technology users is navigation. Sighted users can quickly scan the page, or many pages, just by scrolling through the document with their mouse. Assistive technology users do not use a mouse. They can’t tell where on the screen the mouse IS so that tool isn’t useful to them. Instead, they use tab keys or arrow keys to move from element to element within a document. Assistive technology can be set to read only headings or links, so users can quickly move through the content. They can skim through documents using navigation elements such as Tables of Contents, headings, or links.  

Just because it looks right, doesn’t mean it is

Unless elements in a PDF are coded properly, they don’t function as intended for someone using assistive technology.

Headings

Bold or large font doesn’t define a line of text as a heading for an assistive technology user. Formatting isn’t interpreted by assistive technology.  The heading must be digitally tagged as a heading. Then the AT user can set their technology to read just the headings, and quickly skim through the PDF’s contents to find what they need. 

Table of Contents (TOC)

Without proper links and coding, a table of contents is just a list. Or even worse, it is just a stream of text and numbers without relationships. Tables of Contents need to be tagged as lists with active links so an AT user can easily read through the list and then click on the item of interest.  Sighted users will find a TOC with active links more usable as well.  

Reading Order

What a sighted person sees on the page isn’t always how the AT will read it. Not all documents are read right to left and top to bottom. Imagine a trifold brochure or a complex page of text and images. Or a digital magazine with callouts and other articles referenced…

How a document is created can affect the digital reading order. This is true even if it appears correct to someone reading it visually. If a paragraph was inserted after the introduction, it should be read second. But if the digital tag for that paragraph of text doesn’t reflect the correct reading order, it might be read LAST as it was the last item added to the document.  

Reading order always has to be checked, and any automated tools you might be using to ensure accessibility will NOT be able to tell you if it is correct or not. 

Usability matters

It might not seem like a huge problem to be lacking in navigation tools within a PDF document.  It may seem sufficient that the text is read by assistive technology, and the images are identified.  However, this is not accessible or usable. 

Imagine having to read through a 50-page document on IRS filing regulations when all you needed to know was the deadline for filing.  Or having to read 150 pages of a 500-page textbook to find Chapter 23, which contains the current lesson. Tasks requiring hours of extra effort that do not, in the end, provide the full content are extremely frustrating and result in complaints and lawsuits. Ensure everyone has full access to your digital content and protect your organization from litigation by making your PDFs accessible, navigable, and usable. 

 

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Tammy Albee

Tammy Albee | Content Marketer | Onix Tammy joined Onix after four years experience working at the National Federation of the Blind. She firmly maintains that accessibility is about reaching everyone, regardless of ability, and boosting your market share in the process. "Nobody should be barred from accessing information. It's what drives our modern society."