Conference 16–17 May 2022 📍 Berlin, Germany

PDF Days Europe 2022 — The Hybrid Return After the COVID Gap

PDF Days Europe 2022 took place in Berlin on 16–17 May 2022 — the first European in-person PDF Association conference after the pandemic cancelled the 2020 edition and moved 2021 to virtual. The hybrid format combined in-person attendance with live-streamed remote sessions, a model that has persisted since. Topics included PDF/UA-2 progress, PDF 2.0 tooling maturity, digital signature long-term validation, and structured e-invoicing mandates across EU member states.

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Key takeaways

PDF Days Europe 2022 established the hybrid in-person/online format that has persisted through subsequent events, combining the networking value of in-person with the accessibility of remote streaming.
The draft PDF/UA-2 was introduced publicly for the first time, featuring new structure elements (/Aside, /FENote), WCAG 2.1 alignment, removal of the /B conformance level, and MathML support.
Five years after publication, PDF 2.0 had solid library support but slow end-user tool and organisational adoption — most PDFs were still being created as PDF 1.7.
The PDF Association's reference implementations and test suites for PDF 2.0 were highlighted as key resources for implementors ensuring correct conformance.
Removal of PDF/UA's /B conformance level in PDF/UA-2 was a deliberate signal that accessibility is not a spectrum with a minimum threshold — full conformance is the only standard.

PDF Days Europe 2022 was held in Berlin in May 2022, organised by the PDF Association. After two consecutive virtual editions in 2020 and 2021, the 2022 conference marked the return to in-person attendance in Berlin. It also adopted a hybrid model — live streaming and recorded sessions for remote attendees — which proved successful enough to become the standard format for subsequent events including PDF Days Europe 2025. PDF Days Europe 2022 introduced the draft of PDF/UA-2 to the broader PDF community. The working group had been developing the standard for several years, and the 2022 conference was the first occasion where attendees could engage in detail with the direction of the new accessibility standard. Publication of the final standard was still approximately two years away (ultimately achieved as ISO 14289-2:2024). The conference also addressed the practical state of PDF 2.0 implementation, now five years after publication of ISO 32000-2:2017. The picture was one of steady but uneven progress: major PDF libraries had added PDF 2.0 creation support, but adoption in end-user tools and organisational workflows was slower than specification development had anticipated.

Return to in-person: the hybrid model established

The decision to hold PDF Days Europe 2022 as a hybrid in-person and online event reflected the post-pandemic reality that PDF Association events had developed a genuinely global online audience during the 2020 and 2021 virtual editions. The Berlin venue allowed the core developer and implementor community to meet in person — crucial for the informal technical discussions that are difficult to replicate virtually — while continuing to serve attendees from geographies or organisations that could not justify transatlantic or intercontinental travel for a two-day conference. The hybrid format required significant logistical investment: professional AV setup for streaming, moderated online Q&A alongside in-room questions, and session recording for post-event access. The 2022 experience validated this investment and set expectations that subsequent events would maintain the same model. PDF Days Europe 2025 continued this hybrid approach. The social dimension of the in-person return was noted by attendees: the hallway conversations, evening social events, and face-to-face meetings between implementors who had interacted only online for two years had a qualitatively different character from virtual networking. Several PDF Association working group discussions that had been difficult to advance remotely were resolved or significantly progressed through in-person conversation at the 2022 conference.

PDF/UA-2 draft: new structures and WCAG 2.1 alignment

The draft PDF/UA-2 presented at PDF Days Europe 2022 introduced several significant changes relative to PDF/UA-1 (ISO 14289-1:2012). Sessions provided the first detailed public review of these changes: New structure elements — PDF/UA-2 introduced new element types not present in the PDF 1.7 / PDF/UA-1 structure set. The /Aside element was defined for tangential or supplementary content (sidebars, pull quotes, advertisements) that is related to but not part of the main content flow. The /FENote element replaced the ambiguous use of generic note elements for footnotes and endnotes, providing a semantically specific type. The /DocumentFragment element addressed the common case where a PDF represents a portion of a larger logical document rather than a complete document. WCAG 2.1 alignment — PDF/UA-1 had been developed against WCAG 2.0. PDF/UA-2 aligned with WCAG 2.1 (published June 2018), incorporating the additional success criteria around mobile accessibility, cognitive accessibility, and low vision. For PDF specifically, the most relevant WCAG 2.1 additions were 1.4.10 (Reflow), 1.4.11 (Non-text Contrast), and 1.3.4 (Orientation). Removal of /B conformance level — PDF/UA-1 had two conformance levels: /U (full) and /B (basic). In practice, the /B level had been widely criticised as providing a lower bar that was insufficient for genuine accessibility. PDF/UA-2 removed the /B level entirely, establishing a single conformance requirement. This was a deliberate statement that PDF accessibility was not a spectrum with an acceptable minimum — a document was either fully accessible or it was not. MathML integration — PDF 2.0 had added support for embedding MathML for mathematical content. PDF/UA-2 made proper MathML embedding normative for mathematical expressions, addressing a longstanding gap where mathematical content in PDFs was essentially inaccessible to screen readers unless alternative text was manually provided.

PDF 2.0 implementation: five years in

ISO 32000-2:2017 had been published five years before PDF Days Europe 2022. Sessions provided a status report on where PDF 2.0 implementation actually stood: PDF library support — Major PDF processing libraries had all added PDF 2.0 output support: Apache PDFBox, iText, PDFlib, and others had implemented the key PDF 2.0 features. However, the depth of implementation varied — unencrypted wrapper documents, new encryption algorithms (AES-256 GCM), and the new structure types were not uniformly supported across all libraries. End-user tool support — Adobe Acrobat and Adobe InDesign had PDF 2.0 support in their current versions. Microsoft Word's PDF export did not yet produce PDF 2.0 output (it continued to produce output that aligned with PDF 1.7/PDF/A-1 characteristics). LibreOffice's PDF export remained at PDF 1.5/1.7 level. The vast majority of PDFs being created in 2022 were still created using PDF 1.7 or earlier features. PDF 2.0 features actually used — When PDF 2.0 was being produced, the features most commonly exercised were: the cross-reference stream improvements, the updated encryption, and the new structure elements. The more exotic PDF 2.0 features (associated files, rich media, new colour spaces) were used only in specialist applications. PDF Association reference implementations — The PDF Association had developed reference implementations and test suites for PDF 2.0 that session attendees could use to verify their implementations against known-good documents. These resources significantly lowered the barrier to correct PDF 2.0 implementation and were a concrete output of the PDF Association's standards stewardship role. Interoperability testing — Interoperability issues between different implementations remained a practical concern. Sessions covered specific known interoperability problems — areas where one implementation's output was not correctly processed by another implementation — and the PDF Association's ongoing interoperability testing programme.

Frequently asked questions

What new structure elements did PDF/UA-2 introduce?

PDF/UA-2 (ISO 14289-2:2024) introduced several new structure element types compared to those available in PDF/UA-1: /Aside for tangential content like sidebars and pull quotes; /FENote specifically for footnotes and endnotes (replacing ambiguous use of generic note elements); /DocumentFragment for PDFs that represent part of a larger logical document; /Annot for explicit annotation structure; and /Form for form container structure. PDF/UA-2 is based on PDF 2.0 (ISO 32000-2), which itself introduced additional element types. These new elements provide authoring tools and remediation workflows with more precise semantic vocabulary, enabling more accurate accessibility tagging for complex document layouts.

Why was the PDF/UA /B conformance level removed?

The /B (basic) conformance level in PDF/UA-1 (ISO 14289-1:2012) was intended to define a lower baseline of accessibility requirements for situations where full /U compliance was not achievable. In practice, it was widely criticised because the reduced requirements were insufficient to ensure genuine usability for people with disabilities. Organisations could claim PDF/UA-1/B compliance while delivering documents that were not functionally accessible to screen reader users. The PDF/UA-2 working group decided to remove the /B level entirely, making a clear statement: there is one accessibility standard, and either a document meets it or it does not. Documents that cannot meet full PDF/UA-2 requirements should be clearly identified as non-conformant rather than claiming a lower conformance level that might mislead users about actual accessibility.

How does MathML in PDF/UA-2 improve mathematical accessibility?

Before PDF/UA-2, mathematical content in PDFs was represented as graphics or as sequences of characters and operators in the content stream — neither of which was accessible to screen readers without manually provided alternative text. PDF 2.0 (ISO 32000-2:2017) added support for embedding MathML (Mathematical Markup Language) as associated content for mathematical expressions. PDF/UA-2 makes this normative: mathematical expressions in a PDF/UA-2 compliant document must be represented using properly structured MathML, not just visual rendering. Screen readers that support MathML (including JAWS and NVDA with MathPlayer) can then read mathematical expressions correctly — converting notation like "x squared plus two x minus three equals zero" into spoken form appropriate for users who cannot read the visual notation.

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