Creating accessible PDF documents (part 2/3)
What exactly does an accessible PDF look like?
After our general introduction (part 1/3), what exactly accessibility means, this second part will show how an accessible PDF document can look like.
First of all: In general, a PDF document should always be easy to read, here pay attention to appropriate layout/high contrast, so that even visually impaired people can access all information without difficulty.
It should also be kept in mind that the term accessibility in this context can also refer to many other groups of people, for example illiterate people, people with reading and writing disabilities, or non-native speakers. In this case, however, we are focusing on accessible documents that are created in such a way that they can also be used by visually impaired or blind people. This means that the PDF is prepared in such a way that it can be optimally captured and read by a screen reader.
Rough overview: Most important features that an accessible PDF must have:
- One should make sure that tags are used, i.e. tagged PDF/structured PDF is generally taken into account.
- One should already take the first precautions before creating the document, i.e. use style sheets and think about the layout as well as the text flow.
- Preferences also include adding bookmarks, links and tags to the PDF and checking security settings and speech output, in addition to specifying meta-data such as document titles and the desired display when the document is first opened.
- With regard to accessibility, a PDF can always be optimized further: Concerning Accessibility you should pay attention to the following key points: text flow, contrast mode, reading order, alternative texts for images, data tables, headings, paragraphs, lists, links and bookmarks.
- Basically, the tab order, character language and character encoding also play a role.
Tags in accessible PDF are important first and foremost because they are enormously valuable for the screen reader user. PDF tags can give documents a structure that is important for screen readers to access and that makes it much easier for screen reader users to understand the document. In terms of content, it is important for these people to know where in the text headings, paragraphs, lists or even graphics or data tables can be found.
In addition, structural elements such as the correct reading order, bookmarks or footnotes are important. They influence the order in which the parts of the document are presented via the speech output. In addition, they are important for ensuring that the document components retain their order when converting from PDF to another format, and tags are also important if the document is to flow around correctly (when enlarging the display for visually impaired users).
However, simply creating a PDF with tags is not enough. Accessibility is a broad field and needs to be thought of in a broader way. This aspect will be taken up in the next part 3.
In summary, the most important elements of accessible PDF documents include tags, headings and other styles. Furthermore, the document should either not contain any images or, if it does, they should be provided with alternative text. In addition, bookmarks are important as navigation aids. If it is then ensured that the use of the screen reader is not blocked by security settings, nothing stands in the way of a barrier-free/low-barrier PDF.
Universal Accessibility – The PDF/UA Format
The PDF format offers PDF/A or PDF/X formats, which are adapted to the respective purpose such as printing and archiving. The most important format in the context of accessibility is PDF/UA. UA is the abbreviation for Universal Accessibility.
PDF/UA as a substandard is intended specifically for accessible documents, and is primarily intended to appeal to developers (for example, of programs for creating, reading, processing and checking PDF documents) or providers of assistive technologies. PDF/UA is the industry standard and EN 301549 is the legally binding European standard in this context.
But there are other aspects to consider if you really want to create accessible PDF documents. For example, the WCAG guidelines and other basic usability aspects. So on the one hand, you should observe the PDF/UA standard and be familiar with it if you want to create tagged PDF documents. In addition, one must also deal with the specifications of EN 301549 and the BITV (Barrier-free Information Technology Ordinance). More on PDF/UA and criticisms that the possibilities of accessible PDF documents are still underused or underdeveloped will be included in the upcoming Part 3.
Checking PDF documents for accessibility
The so-called PAC test (PDF Accessibility Checker), now in version 3, can be used to check whether a PDF document meets the most important (testable) conditions for PDF/UA. First of all, one can assume that a PDF is accessible if it passes the PAC test. Whereby, as mentioned above, the WCAG guidelines should also always be observed.
Summary: Creating accessible PDFs – most important requirements:
- Using the right software: A not insignificant aspect of creating accessible documents in PDF format is that you need the right software. It is generally possible to create accessible PDFs with Adobe Acrobat DC, Adobe InDesign and Microsoft Word, for example.
- Observe layout rules for accessible PDFs: Design, layout, didactic structure and linguistic aspects – here you should avoid mistakes in advance, before creating the document.
- The PDF should then be checked for accessibility (PDF/UA validation). In addition, the requirements of the WCAG guidelines and BITV (in german) should be taken into account, because not all accessible PDF documents according to PDF/UA are automatically accessible according to WCAG. The following standards are to be used for validation: Standard ISO-14289-1 as well as EN 301549 (Euro standard). In addition, the so-called Matterhorn protocol with its catalogue of test points serves as orientation. (We will additionally address problems and conflicts that can arise during testing in the upcoming Part 3).
More about PDF/UA: