A key part of making PDFs accessible is ensuring the document is “tagged.” A “tagged PDF” is a type of PDF that includes an underlying tag tree, similar to HTML, that defines the structure of the document. PDF tags make it possible to identify content as headings, lists, tables, etc., and to include alternate text for images. Without tags, none of these accessibility features are possible. Unfortunately, not all PDFs are tagged, and many document-authoring tools are not capable of creating them. Microsoft Word and PowerPoint, and Adobe InDesign, all export to tagged PDF.
If PDFs are not tagged, tags can be added using Adobe Acrobat DC Pro. If you do not have it installed, you will need to install Adobe Acrobat DC Pro. Adobe provides documentation on creating and verifying PDF accessibility. Additional training on adding tags to an untagged PDF, or remediation, is recommended. A good resource is an introduction to Creating Accessible PDFs from LinkedIn Learning.
Auto Tagging
Adobe Acrobat DC Pro includes an option for enhanced auto tagging using cloud-based services, this is not enabled by default and needs to be turned on in the Preference settings in Adobe Acrobat DC Pro. To turn this setting on, select “Preferences” from the Acrobat menu, in the Categories navigation make sure “Accessibility” is selected, then select the box that says “Enable cloud-based auto-tagging for accessibility.”
Using Adobe’s cloud-based auto-tagging feature greatly improves accessibility, however this process can have unpredictable results. Inspecting the tag tree after auto-tagging is recommended.
To add tags to an untagged document, follow these steps using Adobe Acrobat:
- From the Tools tab, open the Accessibility Panel.
- From the Accessibility Panel, select Autotag Document.
Inspect the Tag Tree
To inspect the tag tree, follow these steps:
- From the View menu, select Show/Hide > Navigation Panes > Tags. This will display the tags in descending order from top to bottom.
- Review the tag tree of the PDF to ensure proper semantic structure and proper reading order. Tags may be modified manually, however making changes to the tag tree can have unpredictable results. Save often!
Using the Reading Order Tool
Adding tags to an untagged document using the Reading Order tool is part of a manual tagging or remediation process. For more information, see the Adobe Support documentation on using the Reading Order tool for PDFs. Additional training on using the Reading Order tool to remediate a PDF document manually is recommended.
To add tags using the Reading Order Tool, follow these steps:
- From the Accessibility Panel, launch the Reading Order Tool.
- Marquee the text, then apply the appropriate heading structure from the options in the Reading Order dialogue box.
It is important to note that while tags are essential for PDF accessibility, they do not guarantee accessibility. They must be used properly in order for the PDF to be accessible.