Accessible documents are important to ensure that no one is prevented from accessing digital public services. WCAG 2.1 AA is the legal requirement for PDFs but it is actually created for content on websites. For PDFs there is also a standard called PDF/UA.
WCAG and PDF/UA are similar, but we think it can be instructive and useful to test against PDF/UA as well. With the PAC3 program you can test your documents against PDF/UA. The program can also show how screen readers experience the document and is free to download.
Free PDF Accessibility Checker (PAC 3)
There are many different uses and tools. Two common screen readers are VoiceOver and NVDA.
Download NVDA on the NV Access website
There is also built-in reading in Word and Acrobat. Assistive technology interprets texts in different ways. For example, some follow the reading order and others follow the tag order of the PDF. A fully accessible document increases the chance that it can be used by all assistive technologies.
Creating accessible documents
If the document is a base document and will be edited several times, it is good to make changes to the base document. Otherwise, it is just as well to make the changes directly in Acrobat. Starting from available templates is a good start. Then manual adjustments are almost always needed in Acrobat. Acrobat Pro is needed for almost all accessibility adjustments in PDF. It is a complicated tool but the best available for the task.
Choose simple file names. If you forget to add a title or a link name, it is the file name that will be read. Remember to save the document as you work. Some changes cannot be undone. Title and language are simple changes that can make a big difference to users.
The color of text and graphic elements need to have good contrast. Text on a changing background is often difficult. One tip is to start by checking the graphics manual. You can test colors with the free downloadable Colour Contrast Analyser or the WCAG Color contrast checker.
Color Contrast Analyser on the Paciello Group website
Create real text. Text on image is difficult or impossible for many assistive technologies. In Acrobat you can scan the document and get text via Scanning and OCR. The automatic scanning will not be automatically correct, but requires manual adjustments.
In Word, you can view Formatting marks and view Outline, to see the content of the document.
Headings are an important support for screen readers to navigate texts. Headings need to be marked as proper headings and not just bolded or capitalized.
Images need to be described for those who cannot see the image. Images that do not add any information or emotion should be marked as decorative. In Word, right-click on the image and edit the alternative text.
Tables are difficult to understand for many users with or without assistive technology. Avoid tables if possible. If there are headings in the table, they should be labeled as table headings/TH and indicate whether they are row headings or column headings.
Ideally do not use tables for layout. It may be better to create the content as lists, paragraphs, columns or other to get the desired design. Tables are mainly for tabular data.
Some features in Acrobat Pro that are very useful for accessibility are the tools: Accessibility, Prepare Forms and Scanning & OCR.
Navigation boxes in Acrobat Pro that are very useful for accessibility are Content, Order and Tags.
Tags are important for users to understand what content is what. For example, a heading tag <H1> tells users that a particular text is a main heading. The order is also important for content to be read in the right order.
Reading order also ensures that content is read in the correct order by all assistive technologies. The correct order is usually top to bottom, left to right, but there may be exceptions.
Standard tags in PDF files, Adobe website
The easiest way to create atable of contents is automatically in the basic document and, together with bookmarks, they are important for navigating long documents.
Links need link names that are understandable. Urls are difficult to understand.
Creating forms can be easier to do from an empty tag structure. If you add form fields automatically, you then check that all fields are labeled, correctly named and in the right order. Once the form fields are ready, you can tag the document again.
Remember to save your document as an accessible document, not as a document for printing.