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Conference April 2013 📍 Berlin, Germany

PDF Days Europe 2013 — Berlin: PDF/A-2, PDF/UA Draft, and the Path to Open Governance

PDF Days Europe 2013 was held in Berlin in April 2013. The conference focused on the recently published PDF/A-2 standard, the near-complete draft of PDF/UA (ISO 14289-1), progress toward ISO 32000-2 (PDF 2.0), and the PDF Association's growing role in open governance of the PDF specification.

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Key takeaways

  • PDF/UA-1 (ISO 14289-1:2012) and PDF/A-3 (ISO 19005-3:2012) were both published in 2012 — 2013 was the first conference to present both to a general practitioner audience.
  • PDF/UA requires: all real content tagged; artifacts marked; all figures have /Alt text; reading order in tag tree; no security blocking assistive technologies.
  • PDF/A-3 allows embedded files of any type via the /AF mechanism — the single extension over PDF/A-2 that enabled the hybrid document model (ZUGFeRD, Factur-X, etc.).
  • ZUGFeRD was previewed at the 2013 conference — published June 2014 — as the primary PDF/A-3 use case for hybrid e-invoicing.
  • The PDF Association was beginning work on ISO 32000-2 (PDF 2.0) — community-developed from the start rather than based on an Adobe specification.
  • Tagged PDF is the technical foundation of PDF/UA — but PDF/UA adds normative requirements that turn an optional PDF feature into a mandatory accessibility compliance requirement.
PDF Days Europe 2013 was held in Berlin in April 2013, organised by the PDF Association. It was the first conference following the simultaneous publication of two landmark PDF standards in 2012: PDF/UA-1 (ISO 14289-1:2012) — the first international standard for accessible PDF — and PDF/A-3 (ISO 19005-3:2012) — the first PDF/A variant to allow embedded files of any type. The 2013 conference was therefore a presentation of two newly published standards to practitioners who would be responsible for implementing them, along with early work-in-progress reports from the small number of organisations that had already begun implementation. It was also the first major PDF conference after the PDF/A-2 (ISO 19005-2:2011) publication one year earlier — providing a natural review moment for the full PDF/A family.

PDF/UA-1: the new accessibility standard explained

PDF/UA-1 (ISO 14289-1:2012) was an entirely new type of PDF standard. The PDF/A and PDF/X standards constrained how PDF was produced for archiving and print respectively. PDF/UA constrained how PDF was structured for accessibility — specifically, accessibility to screen readers and other assistive technologies for people with disabilities. The 2013 conference presented the standard's requirements in detail for the first time to a broad practitioner audience: Tagged PDF as the foundation — PDF/UA requires that all real content be represented in the tag tree — the PDF's logical document structure. Tagged PDF was not new (it had been part of the PDF specification since PDF 1.4), but PDF/UA was the first standard to normatively require it. Artifact marking — Non-content elements — page headers, footers, decorative rules, background images — must be marked as artifacts so assistive technologies skip them. Untagged decorative content in the tag tree is read aloud by screen readers as if it were content, creating confusing output. Alternative text for figures — Every Figure element in the tag tree must have an /Alt text description. This was the most immediately actionable requirement for most organisations and the most commonly violated in existing PDF libraries. Reading order in the tag tree — The logical reading order of the document must be reflected in the tag tree. For multi-column layouts, the reading order (column 1 top to bottom, then column 2 top to bottom) must be the tag tree order — not the visual painting order. This was technically challenging for authoring tools. The no-security-blocking requirement — PDF/UA documents cannot use PDF security permissions that disable text selection or content copying. Since assistive technologies rely on text extraction, blocking these permissions breaks screen reader access.

PDF/A-3: the hybrid document model arrives

PDF/A-3 (ISO 19005-3:2012) added a single but significant capability to PDF/A-2: embedded files of any type, not just PDF/A-compliant embedded PDFs. The 2013 conference introduced the PDF/A-3 technical content and presented the use cases that motivated the extension: The core addition — Using the /AF (Associated Files) mechanism with arbitrary AFRelationship values, a PDF/A-3 document could contain XML, CSV, ZIP, or any other format as an embedded attachment. The association relationship (Source, Data, Alternative, Supplement) described how the embedded file related to the PDF content. E-invoicing as the primary motivator — European e-invoicing requirements had driven the standard. The ZUGFeRD standard (about to be published in 2014) would use PDF/A-3 to embed XML invoice data. Sessions previewed the ZUGFeRD architecture and its expected market adoption. The PDF/A family as a whole — With PDF/A-3 published alongside the one-year-old PDF/A-2, the PDF/A family was now three generations old. Sessions provided a comparison: PDF/A-1 for the strictest archiving requirements (no transparency, no embedded files, no encryption); PDF/A-2 for modern features (JPEG2000, transparency, optional content, compliant embedded files); PDF/A-3 for hybrid data exchange (any embedded file type). See PDF/A for the technical distinctions. Validator support — veraPDF (then in early development) and callas pdfaPilot supported PDF/A-3 validation. The PDF Association was coordinating a validation conformance test suite to ensure consistent interpretation across validators.

The PDF Association and open governance of the PDF specification

By 2013, the PDF Association had established itself as the primary steward of the PDF specification's open governance. The transition from an Adobe-controlled format to an ISO-governed open standard was substantially complete: ISO 32000-1 (2008) — PDF 1.7 had been standardised as ISO 32000-1 in 2008, with the specification text largely contributed by Adobe. This was the first step to ISO governance. ISO 32000-2 planning (2013) — The PDF Association was beginning to organise the development of a new edition of the PDF specification — ISO 32000-2, which would become PDF 2.0. Unlike ISO 32000-1, this would be a community-developed specification from the start. PDF standards coordination — The PDF Association was coordinating the development of multiple concurrent standards: PDF/UA-2 (to follow PDF/UA-1), PDF/A-4 (to follow PDF/A-3, based on the future PDF 2.0), and the planned PDF/X-5 and PDF/X-6 standards for print. Technical membership growth — Software companies including Adobe, callas, Foxit, iText, PDFTron (now Apryse), and others were active members. The technical working groups were productively resolving specification ambiguities that had caused implementation divergence for years.

Frequently asked questions

What year was PDF/UA published?

PDF/UA-1 (ISO 14289-1) was first published in 2012. A corrected edition was published in 2014. PDF/UA-2 (ISO 14289-2), based on PDF 2.0, was published in 2024. The original 2012 publication was the first internationally standardised accessibility specification for PDF documents.

What is the /AF entry and what is AFRelationship in PDF?

The /AF (Associated Files) array is a PDF dictionary entry that lists files associated with a PDF document or object. Each entry is a file specification dictionary. The AFRelationship key in the file specification describes how the associated file relates to the containing document: Source — the associated file was the source used to create the PDF; Data — the associated file contains data represented in the PDF; Alternative — the associated file is an alternative representation of the same content; Supplement — the associated file contains supplemental information; EncryptedPayload — the associated file is an encrypted payload. In ZUGFeRD/Factur-X invoices, the XML is typically marked as "Alternative" (same invoice in machine-readable form) or "Data".

Why does PDF/UA require that security settings not block accessibility?

PDF security permissions (the /Encrypt dictionary with /P flags) can restrict text selection, content copying, and other operations. Assistive technologies — screen readers, magnification software, text-to-speech tools — require access to the document's text and structure to function. If a PDF/UA document used security permissions that blocked text copying, a screen reader would be unable to extract the text it needs to read aloud — defeating the entire purpose of the accessibility tagging. PDF/UA therefore requires that documents not use permissions that prevent assistive technology access. This requirement is specified in ISO 14289-1, clause 7.1 (and PDF/UA-2 clause 8.1).

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