Conference October 2024 📍 Online

PDF Accessibility Summit 2024 — Online: PDF/UA-2 Implementation in Practice

The PDF Accessibility Summit 2024, held online in October 2024, focused on practical PDF/UA-2 implementation: updated Matterhorn Protocol checks, validator readiness in PAC and veraPDF, MathML in accessible science PDFs, and real-world remediation cost data from organisations managing large document backlogs.

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Key takeaways

PDF/UA-2 published April 2024 — the Summit was its first focused implementation event six months later
Validator coverage incomplete in October 2024: PAC 2024 was the only free tool with initial PDF/UA-2 coverage
New /Aside and /FENote elements provide better semantics for sidebars and footnotes
/B element deprecated in PDF/UA-2 — requires remediation of PDF/UA-1 content using /B
MathML normatively required for mathematical content — a significant improvement over alt text approximations
LaTeX-to-PDF/UA-2 pipeline was an active development area given scientific publishing importance

The PDF Accessibility Summit 2024, held online in October 2024, was the second edition of the PDF Association's focused accessibility event following the inaugural 2023 Summit. The 2024 edition arrived six months after the April 2024 publication of PDF/UA-2 (ISO 14289-2:2024) — the first major update to the PDF accessibility standard since PDF/UA-1 in 2014. The central question of the 2024 Summit was practical: now that PDF/UA-2 is published, what does implementation actually look like? Where are the validator gaps? Which authoring tools have updated their exports? What do the new structural elements (/Aside, /FENote) actually mean in practice? And how do organisations with large backlogs of PDF/UA-1-compliant documents approach the PDF/UA-2 transition?

PDF/UA-2 in its first six months: validator and tool readiness

PDF/UA-2 introduced meaningful changes that required updates across the entire toolchain — authoring tools, validators, and assistive technologies. By October 2024, the picture was mixed: PAC (PDF Accessibility Checker) — Access For All released PAC 2024 with initial PDF/UA-2 support. The core Matterhorn Protocol 2.0 checkpoints were covered, though some of the more complex new requirements (particularly MathML validation and the new /FENote structure element rules) were still being refined. PAC 2024 was the only free validator with PDF/UA-2 coverage at the time of the Summit. veraPDF — The PDF Association's open-source reference validator had PDF/UA-2 rules under active development. veraPDF's PDF/UA-2 ruleset was not complete in October 2024, with priority given to the highest-impact rules. The development roadmap was publicly tracked at the veraPDF GitHub repository. Acrobat Pro PDF accessibility tools — Adobe had updated Acrobat Pro's tag set to include PDF/UA-2 structure elements, but the auto-tagging and remediation workflows were not yet fully aligned with PDF/UA-2 requirements in October 2024. The accessibility checking tool in Acrobat had not yet been updated to distinguish PDF/UA-1 from PDF/UA-2 compliance. axesPDF and CommonLook — Both commercial tools were in active development of PDF/UA-2 support. The Summit included vendor sessions where tool developers discussed their implementation timelines and the specific PDF/UA-2 requirements they were prioritising.

New structure elements: /Aside, /FENote, and role mapping

PDF/UA-2 introduced new standard structure element types that addressed gaps in the PDF/UA-1 tag set. The Summit provided practical guidance on their use: /Aside — The /Aside element represents content that is tangentially related to the main content flow: sidebars, pull quotes, related content boxes, and annotation notes. In PDF/UA-1, there was no standard element for this type of content — practitioners had to use non-standard role mapping or force content into other element types. /Aside allows screen readers to distinguish sidebar content from main body content and potentially navigate past it. /FENote — The /FENote element (FE = Form/Footnote Entry) represents footnote content anchored to a reference in the main body. PDF/UA-1 required footnotes to be tagged as /Note elements; PDF/UA-2's /FENote provides more specific semantics and clearer placement rules. Summit sessions addressed the correct relationship between the in-text footnote reference (a /Lbl element) and the /FENote content. The /B deprecation — PDF/UA-2 removed the /B element (previously used for bold text styling). Under PDF/UA-2, bold-styled text that is semantically strong or important should use /Strong; purely visual bold styling should use /Span with appropriate attribute markup. This change required remediation of any PDF/UA-1 documents that used /B. Role mapping complexity — Documents that used custom tags with role maps to map to standard PDF/UA-1 types needed to review whether their role maps remained valid under PDF/UA-2. Sessions addressed common role map patterns and how to update them for PDF/UA-2 compliance.

MathML in PDF/UA-2 and accessible scientific documents

One of the most significant technical advances in PDF/UA-2 is the normative requirement to use MathML for mathematical content. Under PDF/UA-1, mathematical expressions had to be represented via alt text — a limitation that produced poor accessible experiences for complex equations. PDF/UA-2 allows MathML content to be embedded in PDF using the /Formula structure element with associated MathML markup. The MathML integration mechanism — MathML content in PDF/UA-2 is stored as associated file attachments (using the /AF mechanism from PDF 2.0, available in PDF/A-3). Each /Formula structure element can reference a MathML fragment as an associated file. Screen readers that support MathML can read the equation using the same MathML processing they use for web content. LaTeX pipeline challenges — Most scientific PDF is generated from LaTeX. The LaTeX PDF pipeline (pdflatex, lualatex, xelatex) does not natively produce MathML-bearing PDF/UA-2 output. Tools for LaTeX-to-accessible-PDF were actively discussed at the Summit: the emerging LaTeXML approach converts LaTeX to HTML+MathML; the latexml2pdf pipeline can produce PDF/UA-2 output from this. Validation of MathML in PDF — Validating MathML conformance within a PDF is a two-layer task: first, verify the PDF/UA-2 structure element is correctly placed; second, validate the MathML fragment itself against the MathML specification. PAC 2024 addressed the structural layer; MathML validation required additional tooling.

Frequently asked questions

Is PDF/UA-1 still valid after PDF/UA-2 publication?

Yes. PDF/UA-1 (ISO 14289-1:2014) remains a valid and enforceable standard. PDF/UA-2 is a separate standard (ISO 14289-2:2024), not a replacement — it covers PDF 2.0 and later. Documents conforming to PDF/UA-1 that are based on PDF 1.7 remain PDF/UA-1 compliant. The European Accessibility Act and EN 301 549 references to "PDF/UA" currently include both versions. For new documents, PDF/UA-2 is preferred if using PDF 2.0 features; for documents based on PDF 1.7, PDF/UA-1 conformance remains the standard. Organisations with large PDF/UA-1 compliant archives do not need to retroactively convert to PDF/UA-2.

What is the Matterhorn Protocol 2.0?

The Matterhorn Protocol is the official PDF/UA test framework, specifying checkpoint statements that can be used to determine PDF/UA conformance. Version 1.x covered PDF/UA-1; Matterhorn Protocol 2.0 (developed alongside PDF/UA-2) adds checkpoints for the new PDF/UA-2 requirements. Each checkpoint is classified as either "machine-verifiable" (can be checked by an automated tool like PAC) or "human-verifiable" (requires human judgment). The Matterhorn Protocol is published by the PDF Association and is the foundation for how PAC and other validators structure their rule sets. An accessible PDF truly conforms to PDF/UA only when all Matterhorn Protocol checkpoints pass — both automated and human-verifiable.

Does the European Accessibility Act require PDF/UA-2?

The European Accessibility Act (EAA, Directive 2019/882) applies to products and services in the EU market from June 2025. For digital documents, EAA compliance references the harmonised standard EN 301 549, which in turn references WCAG 2.1 AA for web content. For PDF documents, EN 301 549 references PDF/UA requirements. The standard currently references PDF/UA-1 (ISO 14289-1) as the applicable PDF accessibility standard; PDF/UA-2 has been proposed for inclusion in the next EN 301 549 update. In practice, organisations should target PDF/UA-2 for new PDF 2.0 documents and PDF/UA-1 for existing PDF 1.7 documents, with PDF/UA-2 becoming the preferred standard as the toolchain matures.

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