Make Sure PDF Documents are Tagged for Accessibility
One of the most important aspects of PDF accessibility is to ensure that PDF documents are tagged. Untagged PDFs can be pretty annoying and difficult to use for screen reader users. In order for screen readers to understand the structure of a document and interpret information in a document, the PDF document needs to be tagged. Tags are invisible labels that provide significant information about the content in a PDF document. Tags can be used to identify paragraph text and headings, assign text alternatives to images, associate table cells with their corresponding header cells, and associate form fields with their corresponding labels.
The most efficient way to properly tag content in a PDF document is to format the document for accessibility in the authoring tool itself. Proper structure and semantics should be utilized before the document is converted to a PDF file. Existing PDF documents can also be tagged and repaired for accessibility using Adobe Acrobat Pro. It is important to note that Adobe Acrobat Pro is the only program that can evaluate and fix accessibility issues in existing PDF files.
To learn more about PDF accesibility, check out Deque University's course on PDF Accessibility Techniques.