How do you add accessibility metadata to an EPUB?

Accessibility metadata tells readers, retailers, and reading systems what accessibility features a title has. It must be declared in two places: inside the ePub3 package document (the OPF file) using schema.org accessibility properties, and in the ONIX feed used for distribution using ONIX code list 196. Both declarations are required by EPUB Accessibility 1.1 and by the EAA's requirement that accessibility features be disclosed to buyers before purchase.

Inside the ePub package, accessibility metadata is expressed as Dublin Core or schema.org properties in the OPF metadata element. The key schema.org properties are: accessibilityFeature (declaring what the ebook has, such as "tableOfContents", "readingOrder", "alternativeText", "MathML", "printPageNumbers"), accessibilityHazard (declaring what the ebook does not have, such as "noFlashingHazard", "noSoundHazard", "noMotionSimulationHazard"), accessMode (declaring the sensory modes through which content is presented, such as "textual", "visual"), accessModeSufficient (declaring which single access mode is sufficient to understand all content, which for a fully accessible text ebook would be ["textual"]), and conformsTo (declaring the conformance standard met, typically "EPUB Accessibility 1.1 - WCAG 2.1 Level AA").

The ONIX feed carries accessibility metadata for the retail and library supply chain using ONIX code list 196. Retailers use this metadata to surface accessibility information to buyers and to filter titles by accessibility feature. ONIX 3.0 supports the full range of accessibility metadata; ONIX 2.1 has more limited support. Key ONIX code list 196 codes include: 00 (no accessibility metadata provided), 10 (no reading system accessibility features actively turned off), 11 (table of contents navigation), 24 (all text in the content is in the reading order), 14 (short alternative descriptions for images), 15 (full alternative descriptions for images), 16 (accessible maths content, MathML), and conformance codes linking to the specific standard and version met.

A common and consequential mistake is declaring features in the metadata that the ebook does not actually have. Claiming "alternativeText" when some images lack alt text, or claiming conformance to EPUB Accessibility 1.1 without having validated the file, creates false expectations for readers who rely on those features and potential liability for the publisher. Accessibility metadata must be verified against the actual content of the file. The ACE by DAISY SMART report provides a machine-readable basis for populating metadata programmatically and can help reduce manual error.

Publishers who operate in multiple markets should be aware that some retailers have begun requiring specific metadata codes as a condition of listing accessible editions. Ensuring that your ONIX feed carries complete and accurate accessibility metadata is therefore both a standards requirement and a commercial necessity. Metadata consistency, meaning the same features declared in both the ePub package and the ONIX feed, is checked by some retail ingestion systems and discrepancies can cause rejection or incorrect classification.

The approved copy also has to cover ONIX accessibility metadata, Schema.org accessibility metadata, each of which a publisher expects answered plainly rather than named in passing.

Nothing on this page has been reviewed. Its provenance is recorded as unverified in the content ledger until somebody signs it off.

The approved copy also has to cover ONIX accessibility metadata, Schema.org accessibility metadata, each of which a publisher expects answered plainly rather than named in passing.

Nothing on this page has been reviewed. Its provenance is recorded as unverified in the content ledger until somebody signs it off.

The approved copy also has to cover ONIX accessibility metadata, Schema.org accessibility metadata, each of which a publisher expects answered plainly rather than named in passing.

Nothing on this page has been reviewed. Its provenance is recorded as unverified in the content ledger until somebody signs it off.

The approved copy also has to cover ONIX accessibility metadata, Schema.org accessibility metadata, each of which a publisher expects answered plainly rather than named in passing.

Nothing on this page has been reviewed. Its provenance is recorded as unverified in the content ledger until somebody signs it off.

The approved copy also has to cover ONIX accessibility metadata, Schema.org accessibility metadata, each of which a publisher expects answered plainly rather than named in passing.

Provisional paragraph. An approved version explains how accessibility metadata is decided in practice, who signs it off, and what a publisher has to supply before the work can start.

Provisional paragraph. It will set out where accessibility metadata sits in the production line, which steps depend on it, and what goes wrong downstream when it is skipped.

Provisional paragraph. The approved text names the file formats involved in accessibility metadata, the checks each one needs, and the point at which a title is considered finished.

Provisional paragraph. Here the approved copy answers the cost question about accessibility metadata honestly: what drives the price, what a publisher can do in-house, and what is worth buying.

Provisional paragraph. It compares the common approaches to accessibility metadata, says which suits a small list and which suits a large one, and does not pretend the answer is the same for both.

Provisional paragraph. This is where the approved copy handles the edge cases in accessibility metadata — tables, formulas, footnotes, illustrations — rather than leaving them to a support ticket. Provisional note 1: the approved copy will say more here about accessibility metadata than a placeholder can. Provisional note 2: the approved copy will say more here about accessibility metadata than a placeholder can. Provisional note 3: the approved copy will say more here about accessibility metadata than a placeholder can. Provisional note 4: the approved copy will say more here about accessibility metadata than a placeholder can. Provisional note 5: the approved copy will say more here about accessibility metadata than a placeholder can.

Nothing on this page has been reviewed. Its provenance is recorded as unverified in the content ledger until somebody signs it off.