Conference 14–15 March 2016 📍 Berlin, Germany

PDF Days Europe 2016 — Berlin: PDF/A, PDF/UA, and the Road to PDF 2.0

PDF Days Europe 2016 was held in Berlin on 14–15 March 2016. The event focused on PDF/A long-term archiving in European regulatory contexts, the growing PDF/UA accessibility movement ahead of new EU public sector legislation, and the progress of the then-draft PDF 2.0 (ISO 32000-2) specification.

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Key takeaways

PDF/UA-1 was four years old by 2016 — enterprise adoption was growing but most government PDF libraries were far from compliant.
EU Web Accessibility Directive (then in final negotiation) would make PDF/UA a legal compliance requirement for EU public sector bodies from 2019.
PDF 2.0 final draft reviewed — key changes: AES-256-GCM encryption, new structure elements, XFA deprecation, removed annotation types.
PDF/UA-2 (to be based on PDF 2.0) was in early planning — would be published as ISO 14289-2:2024.
ZUGFeRD PDF/A-3 e-invoicing accelerating in Germany; Factur-X equivalent developing in France.
EN 16931 European e-invoicing standard development underway — ZUGFeRD/Factur-X alignment was a key question.

PDF Days Europe 2016 was held in Berlin in April 2016, organised by the PDF Association. The conference arrived at a critical juncture: the EU Web Accessibility Directive was then in final negotiation (it would be adopted in October 2016), and ISO 32000-2 (PDF 2.0) was approaching the final ballot stage, with publication expected in 2017. For the accessibility community, 2016 was the year that PDF/UA (ISO 14289-1, published 2012) was transitioning from early adoption to measurable mainstream deployment — four years after publication, enterprise and government organisations were beginning to implement it at scale and reporting real-world tooling experiences. For the invoicing community, PDF/A-3 e-invoicing under the ZUGFeRD standard was accelerating in Germany and France, driven by European e-invoicing mandates entering national legislation.

PDF/UA adoption: four years after publication

ISO 14289-1 (PDF/UA-1) was published in 2012. By 2016, four years of implementation experience had accumulated. Sessions at PDF Days Europe 2016 reported on the state of that experience: Authoring tool support — Microsoft Word, Adobe InDesign, and iAccessibility's axesPDF were the primary pathways for creating PDF/UA-compliant output. Word's PDF export had improved to produce reasonable tag structures for simple documents; InDesign required more manual tagging configuration but could produce high-quality accessible PDFs for complex layouts. The PAC (PDF Accessibility Checker) validator, maintained by the PDF Association, had become the de facto validation tool. Remediation at scale — Organisations with large legacy PDF libraries were grappling with remediation scope. Automated tagging tools (axesPDF, CommonLook, Adobe Acrobat Pro's auto-tag feature) could accelerate the process but required manual review for complex documents. The cost per document for high-quality remediation remained significant for organisations with tens or hundreds of thousands of PDFs. Legal driver emerging — The pending EU Web Accessibility Directive was creating urgency in the public sector. Government agencies were beginning to ask "what percentage of our PDF output is PDF/UA compliant?" for the first time. The answer was typically low. WCAG 2.0 and PDF/UA relationship — Sessions clarified the relationship between WCAG 2.0 (the web content accessibility guideline) and PDF/UA. PDF/UA compliance was the mechanism for achieving WCAG success criteria for PDF documents in scope of European accessibility legislation.

PDF 2.0 (ISO 32000-2): final draft review

The final draft of PDF 2.0 was available for review at the time of the 2016 conference. Sessions walked through the key changes implementors needed to plan for: Object streams and cross-reference streams — Both had been introduced in PDF 1.5 and were mature. PDF 2.0 did not change these, but clarified some ambiguous specification text. See PDF Cross-Reference Stream for background. New optional content features — PDF 2.0 added the ability to specify optional content (layers) usage intents more precisely, enabling more reliable layer behaviour across viewers. Cryptographic algorithm updates — The addition of AES-256-GCM (authenticated) encryption was previewed. Implementors were given time to plan for the new algorithm. New/removed annotations — PDF 2.0 removed several annotation types (Trap Net, 3D) and added new properties to existing annotations. The /RichMedia annotation was removed. Structure element additions — The new structure elements (/Aside, /FENote, /H, /DocumentFragment) were previewed. These were directly relevant to PDF/UA authoring tool development. PDF/UA-2 planning — With PDF/UA-1 based on PDF 1.7, a new version (PDF/UA-2) based on PDF 2.0 was discussed. This would begin formal development shortly after PDF 2.0 publication and would eventually be published as ISO 14289-2:2024.

PDF/A-3 e-invoicing: ZUGFeRD and Factur-X momentum

PDF/A-3 (ISO 19005-3:2012) had introduced the ability to embed arbitrary file types within a PDF/A document using the associated file (/AF) mechanism. The ZUGFeRD hybrid invoice standard used this capability to embed structured XML invoice data (ZUGFeRD XML) inside a PDF/A-3 document — creating an invoice that is both human-readable (the PDF) and machine-processable (the embedded XML). By 2016, ZUGFeRD adoption in Germany was accelerating. The German government was advancing e-invoicing legislation. In France, the equivalent standard (Factur-X) was being developed. Sessions at PDF Days Europe 2016 reviewed: - The ZUGFeRD 1.0 implementation experience — what worked, what common errors appeared - Cross-border compatibility between German ZUGFeRD and French Factur-X - ERP (Enterprise Resource Planning) system support — SAP, Oracle, and Microsoft Dynamics were at various stages of ZUGFeRD support - The forthcoming EU Directive on electronic invoicing in public procurement (Directive 2014/55/EU), which mandated a European standard for e-invoicing (EN 16931) — and how ZUGFeRD/Factur-X would align with it

Frequently asked questions

What is ZUGFeRD and how does it use PDF/A-3?

ZUGFeRD (Zentraler User Guide des Forums elektronische Rechnung Deutschland) is a German hybrid e-invoice standard that combines a human-readable PDF/A-3 document with an embedded XML file conforming to the ZUGFeRD data model. The PDF/A-3 document is the invoice PDF that a human can read; the embedded XML (attached using the /AF associated file mechanism) is machine-processable by accounting and ERP systems. This hybrid approach allows transition to e-invoicing without requiring all parties to adopt a purely electronic format — the PDF is backward-compatible with existing paper/PDF-based workflows. The equivalent French standard is Factur-X. Both are compliant with the EN 16931 European e-invoicing standard.

What is the difference between PDF/UA-1 and PDF/UA-2?

PDF/UA-1 (ISO 14289-1:2012) is based on PDF 1.7 (ISO 32000-1). PDF/UA-2 (ISO 14289-2:2024) is based on PDF 2.0 (ISO 32000-2). The key differences: PDF/UA-2 removes the /B (basic) conformance level (only one level of conformance now), adds support for new PDF 2.0 structure elements, tightens requirements for MathML, and aligns with WCAG 2.1 success criteria. Most significantly, PDF/UA-2 makes previously optional requirements mandatory — meaning some documents that passed PDF/UA-1 validation need updates to pass PDF/UA-2.

What were the EU public sector accessibility compliance dates under the Web Accessibility Directive?

The EU Web Accessibility Directive (Directive 2016/2102) set phased compliance dates for EU public sector bodies: new websites had to comply by 23 September 2019; existing websites by 23 September 2020; mobile applications by 23 June 2021. PDF documents published as part of a public sector website or mobile app are in scope if they were published or substantially revised after the website compliance deadline. This meant any public sector PDF published from September 2019 onwards was expected to meet PDF/UA requirements (via EN 301 549).

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