GAAD 2026: Advancing Accessible PDF

The  world is, of course, changing. Global Accessibility Awareness Day is all about pushing for change in the right direction. The advent of capable AI is triggering reconsideration of many previously straightforward considerations, including with respect to accessibility.

As AI researcher HuggingFace noted, the world’s “higher information density” content tends to occur in PDF files. There are many reasons for this, but the significance of this fact, when it comes to accessibility awareness, is that an accessible world requires accessible PDF files.

Machine / Human →
Deterministic / Non-deterministic

When the Matterhorn Protocol was first developed, over 10 years ago, the PDF Association established a distinction between “human” and “machine” checks for PDF/UA conformance. The objective was to provide guidance to developers and users on how to address the various requirements established in ISO 14289, the ISO standard for accessible PDF.

Given the prevailing state of the art this distinction made sense at the time. We’ve since learned, however, that the Matterhorn Protocol has been misunderstood by some, leading to the document’s so-called “human” vs. “machine” checks being treated as legal requirements for accessibility auditors.

The PDF Association, and indeed, the authors of the Matterhorn Protocol, never intended this interpretation. These designations were not meant to be understood as legally-binding classifications or as statements about what technology is permanently capable of doing. Rather, the choice of terms reflected a practical distinction between deterministic and non-deterministic assessment.

A deterministic check is one for which software can precisely determine conformance from the PDF file itself, using objective rules. For example, the presence or absence of required structural elements and language declarations and the validity of certain syntax conditions, may be evaluated mechanically. These checks can be implemented consistently and produce repeatable results.

By contrast, so-called “human checks” are not so black-and-white, and involve judgment. They may require evaluating whether alternative text is appropriate, whether reading order reflects the author’s intent, whether headings accurately represent document structure, or whether tags convey the correct semantics. Such questions depend on context, purpose, and meaning, not merely file syntax.

This clarification is increasingly important as AI changes the practical boundary between manual and automated accessibility creation, auditing and remediation. AI may enable machines to perform tasks that were historically assigned to humans. However, that does not automatically transform the result to deterministic. AI-supported accessibility assessment may be useful, but can still be probabilistic, dependent on context, and subject to error (hallucinations). 

Accordingly, the PDF Association will soon rephrase its guidance, replacing “machine” and “human” checks with “deterministic” and “non-deterministic”. The new terminology emphasizes that this critical distinction should be read as a statement about reliability, not legality or labor allocation.

Community voices

We asked our Working Group chairs to offer their thoughts to mark the 14th annual Global Accessibility Awareness Day.

Markus Erle

axes4, Co-Chair, PDF Accessibility LWG

Accessibility awareness is where it starts. But awareness alone does not create accessible PDFs. The real challenge is bridging the implementation gap. That’s exactly why the Techniques for Accessible PDF exist.

Developed by an international working group hosted by the PDF Association, they provide vendor-neutral, practice-oriented guidance grounded in real-world expertise and shared industry consensus.

And instead of abstract requirements, the Techniques use small, atomic PDF examples focused on one implementation pattern at a time: A level-3 heading. A multi-line link. A structured list. A linked figure.

Tiny PDF examples that make accessibility tangible directly in the document itself.

Because with PDF accessibility, “just Google it” is not enough. We need reliable, understandable, and approachable knowledge sources that help turn accessibility from isolated expertise into scalable practice.

Create awareness AND bridge the implementation gap.

Frank Mittelbach

LaTeX Project, Co-Chair, LaTex Project LWG

For many years, the LaTeX community has understood that scientific communication is only complete when it can be read, searched, navigated, and reused by everyone. That principle is especially important for mathematics in PDF, where visual fidelity does not imply that the content is accessible.

Recent progress in the LaTeX Tagged PDF project marks an important shift. Accessibility is no longer being treated as a late-stage repair problem or as something authors must approximate manually after publication. Instead, LaTeX is being extended so that the accessible tagging for structures such as sections, lists, tables, figures, cross-references, and mathematical formulae is generated at the same time as, and integrated with, the traditional typeset output.

For mathematics, this is particularly significant. By connecting LaTeX’s representation of formulae with MathML structures in PDF, assistive technologies can receive precise, navigable information, far superior to approximations delivered via alternative text.

Much engineering work remains across packages, authoring practices, validators, PDF processors, and assistive technologies. But with PDF/UA-2, PDF 2.0, and ongoing LaTeX development, accessible mathematical publishing is fast becoming a practical production objective rather than an aspiration.

Zak Kinsey

TargetStream Technologies, Co-Chair, PDF/UA Processor LWG & PDF Accessibility LWG

Global Accessibility Awareness Day is ultimately about reducing barriers, and that requires accessibility to be built into the technologies people use every day, not treated as an afterthought. Our work with the W3C on the forthcoming PDF-AAM (PDF Accessibility API Mappings specification) focuses on making PDF accessibility more consistent and interoperable across assistive technologies, browsers, operating systems, and reading environments. In practical terms, that means defining how the semantic information inside accessible PDFs should be exposed to screen readers and accessibility APIs so that users with disabilities receive a predictable and usable experience regardless of platform or software choice.

Within the PDF Association’s PDF Accessibility Liaison Working Group, our focus is on helping organizations, developers, and remediators understand how to create truly accessible PDF documents through practical implementation guidance. While standards are essential, many organizations struggle with the “how” of accessibility. The Techniques for Accessible PDF initiative was created to provide clear, publicly available guidance that translates technical accessibility requirements into actionable best practices that authors, developers, remediation specialists, and software vendors can realistically apply in production environments. 

Birgit Peböck

barrierefrei PDF OG., Co-chair, PDF Accessibility LWG

Global Accessibility Awareness Day (GAAD) aims to raise awareness of digital accessibility and share knowledge.

The PDF Accessibility Liaison Working Group (LWG) develops techniques to provide practical support for the accessibility of PDF documents. It represents consolidated knowledge from various stakeholders in the field. Standardization experts, software developers, trainers, remediators, and WCAG experts work together.

This knowledge drives document accessibility forward and thus advances the goals of GAAD.

Klaas Posselt

Einmanncombo, Co-chair, PDF/UA TWG

21 May 2026 marks the 15th anniversary of Global Accessibility Awareness Day (GAAD). Its aim is to encourage everyone to think about digital access and inclusion for the more than one billion people worldwide who live with a disability.

The PDF Association’s PDF/UA Technical Working Group (TWG) is making a concrete technical contribution to this: it is driving forward the development of ISO 14289 (PDF/UA), the standard for accessible PDF documents, and brings together PDF software developers and accessibility experts within a vendor-neutral framework.

ISO 14289-2 (PDF/UA-2) represents the outcome of ten years of collaborative work as an international standard – a specification for accessible and reusable PDF 2.0 files, offering benefits and improvements for everyone who works with PDF documents. The standard is complemented by practical resources such as the Matterhorn Protocol and the Tagged PDF Best Practice Guide. The PDF Association has also ensured that PDF/UA-1 was the world’s first ISO standard to meet accessibility requirements itself.

GAAD serves as a reminder that digital inclusion requires a robust technical foundation – the TWG delivers exactly that.

Paul Rayius

PDFix, Co-Chair, PDF/UA Processor LWG

The PDF/UA Processor Liaison Working Group's members are passionate about the accessibility and usability of PDF documents. The group's mission is to help ensure PDF processors and assistive technologies handle PDFs so that they truly are accessible and usable by all.  PDF accessibility might start with content considerations, such as color use, contrast, and the use of headings.  And, of course, the next "logical" piece is the proper tagging, and so on, of that content.  But if processors and assistive technologies don't know how to then handle those tags, attributes, and other "things" in PDFs, then it might all be for nothing. 

The PDF/UA Processor LWG works closely with developers and members of the W3C, to ensure that PDF content is handled not only correctly but also consistently across various platforms and with different devices. It's technical work but it's also a lot of fun, in addition to being crucially important.