Conference April 2015 📍 Berlin, Germany

PDF Days Europe 2015 — Berlin: PDF/A-3, ZUGFeRD Launch, and Accessibility Progress

PDF Days Europe 2015 took place in Berlin in April 2015. The event marked the first anniversary of the ZUGFeRD e-invoicing standard and reviewed early adoption progress. Sessions also covered PDF/A-3 practical deployment, PDF/UA accessibility tooling maturity, and the ongoing development of the PDF 2.0 specification.

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Key takeaways

PDF/A-3 three years after publication: ZUGFeRD was the flagship deployment; other sectors (medical, legal, engineering) beginning to adopt the hybrid document model.
PDF/UA enterprise deployments underway — automated tagging accelerates the process but human review remains essential for complex document quality.
Screen reader testing with JAWS and NVDA remains the definitive PDF/UA quality test — passing PAC does not guarantee screen reader usability.
eIDAS regulation adopted July 2014, effective July 2016 — PAdES profiles (B/T/LT/LTA) map PDF signature capabilities to eIDAS legal requirements.
Long-term signature validation (LTV) via PAdES-LT/LTA essential for archival documents needing signature verification beyond certificate validity periods.
PDF 2.0 (ISO 32000-2) actively in development — final publication expected 2017.

PDF Days Europe 2015 was held in Berlin in April 2015, organised by the PDF Association. The conference examined three standards that had been published in 2012 and were now — three years later — in real-world enterprise deployment: PDF/A-3 (ISO 19005-3), PDF/UA (ISO 14289-1), and the ZUGFeRD hybrid invoice standard. Alongside the standards review, the first anniversary of the ZUGFeRD e-invoicing standard was a central event topic — ZUGFeRD had been published in June 2014 and German enterprise adoption was being reviewed for the first time. Sessions also previewed the ongoing work on ISO 32000-2 (PDF 2.0), then in active drafting.

PDF/A-3 in practice: hybrid document exchange

PDF/A-3 (ISO 19005-3:2012) extended PDF/A-2 by allowing arbitrary file types to be embedded as associated files — not just PDF/A or PDF documents, but also XML, CSV, ZIP, or any other format. This removed the restriction in PDF/A-1 and PDF/A-2 that required embedded files to themselves be PDF/A compliant. Three years after publication, sessions at PDF Days Europe 2015 reviewed real-world PDF/A-3 deployment: ZUGFeRD as the primary PDF/A-3 success story — The ZUGFeRD hybrid invoice standard was the highest-profile PDF/A-3 deployment. The model — a PDF/A-3 human-readable invoice with an embedded machine-readable XML — proved the value of PDF/A-3's relaxed embedded file constraint. See PDF/A for archiving context. Beyond invoices: other PDF/A-3 use cases emerging — Medical records with embedded HL7/FHIR data, legal contracts with embedded case management XML, engineering drawings with embedded CAD data, and academic papers with embedded datasets were all discussed as emerging PDF/A-3 use cases. Archiving implications — Embedded files in PDF/A-3 are not themselves required to be PDF/A compliant. Long-term archive systems needed to plan for whether they would preserve, index, and render embedded files alongside the PDF container. OAIS (Open Archival Information System) conformance for PDF/A-3 archives was examined. Creator tool and validator support — Apache PDFBox, iText, PDF/A libraries from callas software and Datalogics had all shipped PDF/A-3 creation and validation support. Interoperability testing was conducted at the conference, with results shared with implementors.

PDF/UA accessibility: early enterprise deployments

By 2015, PDF/UA (ISO 14289-1) had been published for three years and a handful of enterprise organisations had completed or were mid-way through significant accessible PDF implementations. Sessions shared early experiences: Government deployments — The UK Government Digital Service and several German federal agencies had committed to accessible PDF outputs. The practical challenges — retrofitting existing templates, training authors, integrating validation into document workflows — were reviewed in detail. Financial services — Annual reports, fund fact sheets, and customer statements were being targeted for PDF/UA compliance, driven by emerging accessibility regulations and customer expectations. The challenge of producing accessible PDF from data-driven financial report generation pipelines was a recurring theme. Automated tagging quality — Acrobat Pro's auto-tag feature and specialist tools (axesPDF, CommonLook) could produce initial tagged PDFs, but the quality required significant manual post-processing for complex multi-column layouts, figures with captions, and tables. The "last mile" of PDF/UA compliance was human review and correction. Testing approaches — Sessions reviewed the testing workflow: automated validation with PAC (PDF Accessibility Checker), followed by screen reader testing with JAWS and NVDA. The gap between passing PAC validation and genuinely usable-by-screen-reader PDFs was highlighted — automated validation catches structural errors but not quality-of-experience problems.

Digital signatures: European eIDAS context

The eIDAS regulation (EU 910/2014) was adopted in July 2014 and would become fully effective in July 2016. Sessions at PDF Days Europe 2015 addressed its implications for PDF digital signatures one year before full implementation: PAdES profiles — The ETSI PAdES (PDF Advanced Electronic Signatures) standard defined several levels of PDF signature corresponding to different long-term validation needs: PAdES-B (basic), PAdES-T (with timestamp), PAdES-LT (with validation data), and PAdES-LTA (archival). These profiles provided the technical mapping between PDF signature capabilities and eIDAS requirements. Long-term signature validation (LTV) — For documents that need to be verified years after signing — archival contracts, legal documents, land registry records — the signature must include embedded validation data (certificate chain, revocation information, timestamps) that allows verification without contacting online validation services. PAdES-LT/LTA addressed this need. Trust service providers — eIDAS established the EU Trust Lists — national lists of qualified trust service providers whose certificates could be used for qualified electronic signatures. PDF signing workflows using QES needed to verify against these lists. See Digital Signatures in PDF for technical background.

Frequently asked questions

What is PAdES and what are its levels?

PAdES (PDF Advanced Electronic Signatures) is an ETSI standard (ETSI EN 319 100 series) that profiles PDF digital signatures for compliance with eIDAS. The main levels are: PAdES-B (baseline — a basic CMS signature within a PDF); PAdES-T (adds a timestamp token, providing proof of time); PAdES-LT (adds embedded certificate chains and revocation data — verification does not require online checks); PAdES-LTA (adds additional archive timestamps to protect against cryptographic algorithm ageing — suitable for very long-term archival). See Digital Signatures in PDF for context.

What is an associated file in PDF/A-3?

An associated file in PDF/A-3 is an embedded file attached to a PDF document (or to a specific object within the document) using the /AF (Associated Files) array. Unlike simple file attachments, associated files have a defined relationship to the containing document — the AFRelationship key describes the nature of the relationship (Source, Data, Alternative, Supplement, EncryptedPayload, Unspecified). In ZUGFeRD/Factur-X invoices, the relationship is "Alternative" (the XML is an alternative machine-readable representation of the same invoice content) or "Data" (the XML provides the data layer). Associated files can be attached to the document catalogue, pages, or specific objects within the document.

What is the difference between PDF/A-2 and PDF/A-3?

The only difference between PDF/A-2 and PDF/A-3 is that PDF/A-3 allows embedded files of any type via the associated file mechanism — not just PDF/A-compliant embedded PDFs as in PDF/A-2. Every other technical requirement is identical. In practice, this single difference opened up the hybrid document model: a PDF/A-3 document can contain an embedded XML, CSV, ZIP, or other structured data file alongside the human-readable PDF content. This is the basis of the ZUGFeRD/Factur-X e-invoicing model and the emerging medical, legal, and scientific data attachment use cases.

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