Accessibility Best Practices: Tagged PDF

PDF is a publication format, and almost all PDFs were created from a production application, most commonly Word, InDesign, or PowerPoint. The native file is exported and converted to PDF for publication. Using best practices for creating accessible documents includes exporting as a “tagged PDF”; almost all production applications will have an export setting to create these PDF tags. Proper order and syntax of tags is essential for Section 508 compliant documents.

The substructure of a tagged PDF includes markups that, when properly applied, help to optimize the reading experience of those who use screen readers and other assistive technology (AT). Proper tagging is a crucial component of achieving a truly accessible PDF, and  can also re-flow to adapt its presentation to different screen sizes, such as a high-quality experience to users of smart mobile devices.

Tags provide a logical structure that governs how  assistive technology “reads” the document. Each tag identifies the associated content element, for example paragraph <P>, heading level three <H3>, list item <LI>, image <Figure>, or table data cell <TD>. The order of the tags defines the reading order. Purely visual elements, such as images that provide visual interest but no meaning, are tagged as background artifacts and disregarded by AT. Tags for meaningful images such as graphs must include alternate text that clearly conveys the same meaning as the visual representation.

Adobe Acrobat can automatically add tags to a PDF, but the result is never satisfactory without careful, knowledgeable human inspection, testing and corrective actions.  Even small errors in the logical structure can render the document incomprehensible to assistive technology users.

While properly constructed tags are essential for an accessible PDF, they are just one element of an accessible, compliant PDF. Careful tagging must be used in combination with other aspects of document accessibility such as properly defined document language, meta data, font size, font embedding, color contrast, and bookmarks to achieve a truly accessible PDF.