Accessible documents are important for a website to be considered accessible. For this purpose, specially designed accessible PDF documents should be incorporated.
Checklist for requirements for accessible PDF documents
The following requirements are important.
- Content must be readable aloud.
- All content must be correctly marked up. This includes, in particular, headings, lists, paragraphs, and tables. The document must be marked as tagged.
- Bookmarks must be included, both in the content and in the tag tree!
- All characters in tagged text content must be clearly convertible to a Unicode character.
- All graphics have an alternative description.
- All non-content elements are marked as artifacts, i.e., invisible to users of assistive technology. This applies in particular to elements that are repeated on every page, such as headers and footers.
- In addition, headers and footers should not contain any essential information.
- The metadata is stored in the document properties.
Warnings in the document
All elements must appear in a logical reading order, i.e., the document must be structured consistently. Warnings are issued when ...
- there is no heading,
- the first heading does not correspond to outline level 1,
- an outline level is skipped.
Language and assistive technologies
- The document language is correctly specified. Larger sections in foreign languages are correctly marked.
- No security mechanisms are activated if possible (the security settings of the PDF document must allow access to the tag structure by assistive technologies). In particular, access by assistive technologies and copying of text are permitted.
- Graphics do not contain long text. Text contained in graphics such as diagrams is always provided in a text alternative, for example as continuous text or a table.
- The file name is self-explanatory.
- The title of the document is displayed in the title bar of Adobe Reader, not the file name.
- There is sufficient contrast in tagged text.
Accessible PDF forms
Additional requirements apply to forms in PDF format. It is important that they can be filled out on screen without further measures. Usability for blind and visually impaired users must be ensured as follows:
- Usability via keyboard, in particular the use of the tab key in a logical order, is ensured.
- Mandatory fields are clearly marked. The input fields can be clearly assigned to each other by labels.
- Incorrect entries are recognizable where possible.
- Conventions are observed in the design. This includes, for example, the usual order for entries such as first name, last name, street, postal code, city, telephone, and so on.
Tables in accessible PDFs
There are additional important requirements for tables in PDFs.
- Tables are read aloud in a logical order. IMPORTANT: If data tables are not structured logically, they are practically unusable for blind people.
- For complex tables, a description visible to blind people is provided.
- Table headings are clearly marked.
