EN 301 549 5.4 -- Preservation of Accessibility Information

For reference only -- not part of a11ybot's automated checks.

What It Is

ETSI EN 301 549 v3.2.1 clause 5.4 -- "Preservation of accessibility information during conversion" -- says that where ICT converts information or communication, it shall preserve all documented non-proprietary accessibility information, to the extent that the destination format can carry it[1]. The obligation attaches to the converter, not the author. Export, import, save-as, copy-paste, transcoding, server-side rewriting, and file-format conversion all count as "conversion" for the purpose of this clause.

Why It Matters

Accessibility metadata is carried in format-specific slots -- the PDF structure tree, the HTML alt attribute, the lang attribute, the <th> / scope association on a table header, the WebVTT cue track on a video, the EPUB Navigation Document. A converter that reads the source but does not know about those slots drops them on the floor. The failure modes are specific and repeatable:

  • Exporting a tagged PDF to Word through a generic extractor and losing the heading level tree, so a screen reader can no longer jump by heading.
  • Copying an HTML table with <th scope="col"> headers into a Google Doc that rebuilds it as a plain <table> with no header association.
  • Saving an EPUB with a Navigation Document and epub:type landmarks to a flat .txt file, which destroys every structural cue at once.
  • Converting a Word document with alt text on an inline image to a PDF whose image object has no /Alt entry.
  • Converting .docx to .html through a library that emits <p> for every paragraph and drops lang, list semantics, and heading levels.
  • Email gateways rewriting HTML to inline-styled tables and stripping role, alt, and lang in the process.

How It Relates to WCAG

WCAG conformance attaches to the final rendered output. Clause 5.4 fills a gap WCAG does not address -- it assigns the duty to the tool in the middle of the pipeline[1]. A converter that satisfies 5.4 does not by itself produce WCAG-conformant content, but it stops silently damaging accessible content produced upstream. When a document arrives at its final destination broken, 5.4 is the clause that points at the converter rather than the original author.

Practical Implications

  • When implementing a format converter, pick libraries that map accessibility metadata slot-for-slot: alt text, heading levels, list semantics, table header association, language attributes, ARIA landmarks or their document-format equivalents (PDF structure types, EPUB epub:type, DOCX styles).
  • Test round-trips with assistive technology, not visual diff. A file that renders identically in a viewer can still have lost its tag tree. Open the converted output in a screen reader and navigate by heading, landmark, and table header.
  • Treat any conversion that drops to a format with fewer accessibility slots (HTML to plain text, tagged PDF to flat PDF, DOCX to RTF) as lossy by definition and warn the user before it runs.
  • CMS render pipelines, email gateways, and ingest-and-republish workflows are conversion steps under 5.4 even when the user thinks of them as "just saving." Audit each hop.
  • Video transcoders must carry caption tracks and audio description tracks through the transcode, not re-encode the picture and drop the sidecar.

Related Clauses

Sources

  • ETSI EN 301 549 v3.2.1, clause 5.4 "Preservation of accessibility information during conversion"[1]
  • W3C ATAG 2.0 (parallel guidance for authoring tools)