Standard
PDF/UA (ISO 14289)
PDF/UA ("Universal Accessibility") is the international standard that defines the technical requirements a PDF file must meet to be reliably accessible to assistive technology. It is an ISO standard, published as ISO 14289, and is maintained by ISO Technical Committee TC 171/SC 2/WG 9, with substantial contribution from the PDF Association, whose PDF/UA Competence Center supports implementation.
Unlike WCAG, which is outcome-oriented and format-agnostic, PDF/UA is prescriptive and format-specific: it states precisely how the internal structures of a PDF must be constructed. The standard exists in two parts. PDF/UA-1 is ISO 14289-1, first published in 2012 and revised as ISO 14289-1:2014; it builds on ISO 32000-1 (PDF 1.7) and remains the version most conformance tools still target today. PDF/UA-2 is ISO 14289-2:2024, published in 2024 and built on ISO 32000-2 (PDF 2.0); it extends accessibility support with improvements such as MathML for mathematical expressions, richer annotation and metadata handling, and refinements to the tagging model.
The core premise is that an accessible PDF must be a properly Tagged PDF carrying a complete and semantically correct logical structure. A conformant file must express reading order explicitly; mark up headings, paragraphs, lists, and tables with correct structure elements; provide alternative text for meaningful images and other non-text content; declare the natural language of the content; correctly identify and label form fields; and distinguish real content from artifacts (decorative or layout-only elements). PDF/UA also imposes requirements on the file itself, such as embedding fonts and setting metadata flags that declare the document as tagged and accessible.
To help implementers and testers, the PDF Association maintains the Matterhorn Protocol, a companion checklist of checkpoints and failure conditions that operationalise the ISO requirements into testable conditions — some machine-checkable, some requiring human judgement. PDF/UA matters because it provides the definitive, unambiguous technical contract for what makes a PDF work with screen readers, braille displays, magnifiers, and voice control. Where WCAG describes the accessible experience, PDF/UA specifies the file-level engineering that makes that experience possible.
How Normfluss checks for it
Normfluss inspects the file against PDF/UA requirements: it confirms the document is tagged, checks that the structure tree is complete and correctly nested, verifies reading order, and detects missing alternative text, untagged content, undeclared language, and improperly marked artifacts or form fields. Many checks map to Matterhorn Protocol failure conditions; the machine-testable subset is automated while items such as whether alt text is meaningful are routed to manual review. Results are PDF/UA conformance within a stated, tool-checkable scope — not a guarantee of legal compliance.