There are two main industry standards to follow when remediating PDFs.
PDF/UA (Universal Access, or ISO 14289)
PDF/UA specifies the requirements an accessible PDF must fulfill, but also the requirements of authoring tools for creating accessible PDFs, readers and assistive technologies. UA stands for Universal Accessibility. PDF/UA is complementary to WCAG and focuses on the technical and PDF-specific aspects and mechanisms relating to digital accessibility.
The PDF/UA standards are based off of four principles called RISE:
- Reliable: Files comply to the greatest possible extent with applicable specifications to facilitate robustness in processing across a wide range of use cases and software.
- Interoperable: Elements of content can be readily exchanged between computing systems without loss of semantics.
- Suitable: Suitability for the widest range of PDF processing applications and use-cases within the intended user population, taking account of special abilities, variations in capabilities, diversity in tasks, and differing environmental, economic and social circumstances.
- Equitable: Equitable solutions provide the same means of use for all users: identical whenever possible; equivalent when not.
PDF/UA validation cannot be done fully with automated checkers - manual review by a human is needed as well.
Web Content Accessibility Guidelines
The WCAG covers 23 PDF Techniques in their success criteria, including Applying Text Alternatives to Images, Providing Interactive Form Controls, and Using table elements for table markup in PDF Documents.
How to Address the Industry Standards in Your Remediation Efforts
Many of the requirements covered in both sets of standards can be handled on the source document side prior to conversion, but the level of effort to remediate the content depends on the original source file (for example, PowerPoint will be much more extensive to remediate on the PDF side) or lack of access to an original source file.