EPUB Accessibility Metadata: What Publishers Must Check

EPUB Accessibility Metadata: What Publishers Must Check

An ebook may work well with screen readers and offer clear navigation. Yet readers may not know about these features if the book's accessibility information is missing.

This is where EPUB accessibility metadata becomes important.

Accessibility metadata tells readers how they can use a digital book. It describes features such as text alternatives, navigation, reading options, and known limits.

For publishers, this information is part of digital book quality. It helps retailers, libraries, and readers understand what an EPUB can offer.

However, adding metadata is not enough. Publishers must make sure every claim matches the finished ebook.

This guide explains how EPUB accessibility metadata works, what publishers should include, and how to review it before distribution.

What is EPUB accessibility metadata?

EPUB accessibility metadata is information stored inside an ebook that describes how readers can access its content.

It can identify available features, such as image descriptions, structured navigation, and text-based reading options.

It can also tell readers about content that may cause access problems.

For example, an illustrated textbook may include alternative text for diagrams. Its metadata can tell readers that these descriptions are available.

Another ebook may include videos with captions. Its metadata can describe that feature.

Publishers should use accurate metadata to explain what a title supports.

Accessibility metadata describes an ebook. It does not make the content accessible by itself.

Why is accessibility metadata important?

Readers use digital books in different ways.

Some people use screen readers to listen to text. Others increase the font size, adjust spacing, or change display colours.

Before choosing an ebook, they may want to know whether it supports these reading needs.

Accurate metadata helps them make that decision.

Consider a student who needs an accessible textbook. The student may want to know whether the book has a working table of contents and descriptions for important diagrams.

Without clear accessibility information, choosing the right edition becomes harder.

Publishers also benefit from reliable records. They can track accessibility features across their catalogues and share accurate details with distribution partners.

What are the main EPUB accessibility metadata fields?

EPUB Accessibility 1.1 defines metadata requirements for publications that follow the specification.

The main properties describe reading modes, accessibility features, and possible hazards.

Other recommended properties provide more detail about how readers can use the publication.

Under EPUB Accessibility 1.1, the first, third, and fourth properties are required. The other two are recommended.

Publishers should use the correct values for the specification and version they follow.

Access mode: How readers receive information

The accessMode property describes the ways readers perceive an ebook's content.

A text-based novel may use the textual mode. An illustrated textbook may include both textual and visual content.

An audiobook or multimedia publication may include audio.

These values describe the content rather than the reader's device.

For example, a book containing diagrams still includes visual information, even when those diagrams have text alternatives.

This distinction helps publishers describe the publication accurately.

Sufficient access mode: Can readers understand the content?

The accessModeSufficient property goes further.

It describes which reading modes allow someone to understand the publication without losing important information.

Consider a textbook with paragraphs and charts.

If the charts have complete text alternatives, readers may be able to understand the content through text alone.

The metadata can describe that option.

However, publishers should not make this claim when key information is still available only through images.

The decision should follow a review of the final content.

Accessibility features: What does the ebook support?

The accessibilityFeature property lists features that help readers use the publication.

These can include text alternatives, structured navigation, and other supported options.

For example, a textbook may include descriptions for meaningful images. Another publication may provide links to page locations that match a print edition.

The publisher should record these features only after confirming that they work.

A feature should not appear in the metadata simply because it was planned during production.

The final file must support the claim.

Accessibility hazards: Are there any risks?

The accessibilityHazard property describes potential hazards in the content.

Some digital publications include flashing effects, motion, or sound that may affect certain readers.

An ordinary text-based book may not contain these features. An interactive educational title may require closer review.

Publishers should check the actual content before reporting hazards or stating that particular hazards are absent.

They should also use the correct controlled metadata values.

A guess is not a suitable basis for an accessibility claim.

Accessibility summary: What should readers know?

An accessibilitySummary gives readers a clear explanation of the book's accessibility features and known limitations.

It should add useful information rather than repeat every metadata property.

For example, the summary may explain that a textbook includes structured navigation and image descriptions but lacks extended descriptions for a few complex charts.

This gives readers a clearer picture of what to expect.

Publishers should write the summary in plain language.

The goal is to communicate useful information, not fill the record with technical terms.

How do you write a useful accessibility summary?

A good accessibility summary answers a simple question:

What can readers use, and what should they know before opening the book?

It should describe confirmed features and any important limits.

For example, a sample summary might read:

"This EPUB includes structured chapter navigation, adjustable text, and descriptions for informative images. Readers can use the book with supported screen readers. Some complex diagrams have separate descriptions."

This is an illustrative example, not a statement about a specific publication.

Avoid vague claims such as "fully accessible" unless the publisher has completed an assessment that supports the claim.

A short, accurate summary is more helpful than a long statement filled with general promises.

For complex titles, the summary may need more detail.

For example, an academic book may have several image-based formulas that require a separate explanation.

The publisher should describe any limits that could affect how readers use the content.

How do EPUB and ONIX accessibility metadata differ?

Publishers often manage accessibility information in two places.

The first is inside the EPUB file. The second is within an ONIX product record.

EPUB metadata describes the accessibility features of the publication itself.

ONIX accessibility metadata carries relevant information through the book supply chain.

This allows retailers, distributors, and libraries to receive accessibility details alongside other product information.

Both records should describe the same publication accurately.

For example, if the EPUB includes image descriptions, its ONIX information should not contradict that feature.

The two records do not need to contain identical text. They need to communicate consistent facts.

What is ONIX Codelist 196?

ONIX Codelist 196 contains values used to describe digital publication accessibility.

Publishers use these values to share structured information with trade partners.

Some values describe navigation features. Others describe text alternatives, accessibility status, or conformance claims.

For example, a publisher may need to communicate that an EPUB offers a structured table of contents or supports page navigation.

The relevant ONIX values help carry those details through the distribution system.

However, publishers should not choose codes based only on assumptions.

The team must confirm that the feature exists and works in the delivered file.

ONIX code lists are updated over time. Publishers should use the current definitions and confirm that their distribution partners accept the selected values.

Why must EPUB and ONIX records match?

Imagine a publisher updates a textbook.

The new EPUB contains improved navigation and descriptions for several diagrams.

The production team updates the EPUB metadata, but the ONIX record still describes the previous edition.

As a result, the retailer may display outdated accessibility information.

The opposite problem can also occur.

An ONIX record may claim that the ebook supports features that are missing from the file.

Both situations create confusion.

Publishers should compare the two records before release.

The review should confirm the correct title, ISBN, edition, file version, and accessibility details.

If the EPUB changes after approval, the team should check whether its metadata needs another update.

What accessibility details should a retailer receive?

Retailers may display selected accessibility details on a product page.

This can help customers decide whether an ebook meets their reading needs.

For example, the product record may describe available navigation, alternative text, or other features.

The exact details shown depend on the retailer and its systems.

A publisher cannot assume that every platform will display all the metadata it sends.

That is why distribution testing matters.

After sending an ONIX record, the publisher should review how the product information appears where practical.

If important accessibility details are missing, the team can check whether the problem lies in the source record, the distribution feed, or the receiving platform.

This review helps turn accurate metadata into information readers can actually find.

Does the table of contents affect accessibility metadata?

Yes. Navigation is an important part of the reading experience.

An EPUB may include a structured table of contents that lets readers move between chapters and sections.

For example, a research book may contain chapters, appendices, references, and a glossary.

A clear table of contents helps readers locate these sections without searching through the entire publication.

However, publishers should not claim that navigation is available without checking it.

The links should lead to the correct sections. Important headings should appear in the intended order.

If the EPUB includes page navigation, those references should also work as expected.

Metadata should describe the navigation features present in the finished file.

For more details, read Gentize's EPUB Page Navigation Guide.

Can digital rights management affect accessibility?

Digital rights management, or DRM, controls how people use and share digital publications.

Some DRM systems or reading platforms may limit certain functions.

Depending on the platform, these restrictions may affect text selection, copying, or reading options.

For readers using assistive technology, such limits can create problems.

Publishers should therefore check how their chosen DRM and distribution systems behave.

For example, an ebook may contain accessible text but still face restrictions in a particular reading environment.

The publisher should not make broad accessibility claims without considering those conditions.

The aim is to ensure that content features remain usable after distribution.

Do all EPUB reading systems work the same way?

No. Different reading systems may support EPUB features differently.

An ebook may open correctly in several applications, but its reading options can vary.

One application may provide more control over font size and spacing. Another may handle navigation or screen-reader output differently.

This does not always mean the EPUB file is defective.

Sometimes the difference comes from the reading software.

Publishers should therefore test the publication in reading systems that matter to the target audience.

For educational titles, this may include platforms used by students and universities.

For trade books, publishers may focus on major consumer reading applications.

The test results can help teams describe the publication and any known limitations more accurately.

How does metadata work for illustrated and fixed-layout EPUBs?

Not every EPUB contains mainly text.

Children's books, comics, illustrated textbooks, and educational titles may use fixed layouts.

These publications can present different accessibility needs.

For example, a fixed-layout textbook may contain text placed around diagrams. A children's book may use illustrations to tell part of the story.

Publishers should check whether the content offers enough information to readers who cannot rely on the visual page.

If important images contain descriptions, the metadata can reflect those features.

However, the publisher should not claim unrestricted text resizing if the publication cannot support it.

The same principle applies to navigation and reading modes.

Metadata should describe the actual format rather than assume every EPUB offers the same reading options.

How should metadata describe complex academic content?

Academic books often contain charts, equations, tables, and technical diagrams.

These elements may need specialist accessibility work.

Consider a mathematics textbook.

If its equations use an accessible representation, the publisher may be able to describe that feature through suitable metadata.

However, it should first confirm that the mathematical content is correct and usable in the intended reading environment.

The same rule applies to charts and tables.

A book should not claim that all complex images have useful descriptions when the team has reviewed only a few of them.

Publishers should agree on what each metadata claim means and what evidence supports it.

For titles with complex visuals, read Gentize's Alt Text for Complex Images in EPUB guide.

What if an EPUB has not been assessed?

Some publishers manage large collections of older ebooks.

Many of these titles were created before current accessibility practices became common.

A publisher may not know whether every book contains accurate structure, descriptions, and navigation.

In that situation, the team should not claim that the entire collection is accessible.

The safer approach is to identify titles that need assessment.

ONIX provides ways to communicate unknown or limited accessibility status.

Publishers can use suitable values when the evidence does not support stronger claims.

Once a title has been reviewed or corrected, its information can be updated.

This creates a more reliable record than assigning the same accessibility status to every book.

Can an EPUB pass validation but still have incorrect metadata?

Yes.

Technical validation and metadata accuracy are related, but they are different checks.

A tool may confirm that a metadata property exists and uses an accepted value.

It may not be able to confirm whether the claim is true.

For example, an EPUB may declare that it contains alternative text.

The property may be technically valid, but some important images may still lack meaningful descriptions.

The same problem can occur with navigation.

A publication may claim to offer a useful table of contents even when some links lead to the wrong location.

Publishers should therefore compare metadata claims with the actual content.

Technical checks help identify errors. Manual review helps confirm that the information is accurate.

What is the best EPUB accessibility metadata workflow?

A clear workflow helps publishers avoid errors between production and distribution.

The steps below focus on metadata rather than general EPUB conversion.

Step 1: Review the approved EPUB

Begin with the final content file.

Confirm the features that the publication actually provides.

This may include navigation, image descriptions, reading options, and other accessibility features.

The metadata team should not rely only on an old production brief.

It should use the approved publication and its QA results.

Step 2: Check the package metadata

Next, review the accessibility metadata inside the EPUB.

Check whether the required properties are present and use appropriate values.

Look closely at any statements about sufficient access modes, hazards, and accessibility features.

The information should match the file.

If a feature is missing, the team should correct the content or update the claim.

Step 3: Review the accessibility summary

The summary should explain the most useful features and known limitations.

Check whether the wording is clear.

Avoid marketing language that promises more than the file provides.

Where possible, give readers enough information to understand how they can use the book.

The summary should complement the structured metadata.

Step 4: Prepare the ONIX record

Once the EPUB information is approved, update the related ONIX metadata.

Use the appropriate values from the current code list.

Check that the record belongs to the correct ISBN and edition.

If the title has several digital versions, keep their records separate.

A fixed-layout EPUB may not have the same accessibility features as a reflowable edition.

Step 5: Compare and approve both records

Before distribution, compare the EPUB and ONIX information.

Confirm that features, limitations, and any conformance claims are consistent.

The team should also record the approved file version.

If later corrections change the accessibility features, review the metadata again.

This helps prevent outdated information from reaching readers.

EPUB accessibility metadata checklist

Publishers can use the following checklist before releasing a title.

A checklist helps teams apply the same standards across titles.

However, it should support the wider QA process rather than replace content testing.

Common EPUB metadata mistakes publishers should avoid

Several problems can occur when teams treat metadata as a simple data-entry task.

Copying metadata from another title

A publisher may use one completed book as a template for the next.

Templates can save time, but they can also carry incorrect accessibility claims.

A novel, textbook, and illustrated children's book may provide very different features.

Review each title before using the same values.

Claiming features before testing them

A production plan may include image descriptions or page navigation.

However, the final EPUB may still contain missing descriptions or broken links.

Metadata should reflect the approved file, not the planned work.

Ignoring known limitations

A publication can support useful accessibility features while still having some limits.

Publishers should communicate those limits clearly.

Accurate information helps readers decide whether the book meets their needs.

Updating the EPUB but not ONIX

Accessibility corrections can change what a publication supports.

If the EPUB metadata changes, the ONIX record may also need an update.

Keep both records aligned with the current edition.

Assuming validation proves every claim

A valid file may still contain inaccurate accessibility information.

The team should check the content and the metadata.

Both are needed for a reliable release.

How can publishers manage accessibility metadata across a backlist?

Large publishing collections often contain EPUB files from different periods.

Some titles may have complete accessibility metadata. Others may contain no useful information.

Several may require content remediation before their accessibility features can be described.

A practical starting point is to review the catalogue and group titles by status.

For example, a publisher could identify titles that are ready for distribution, titles needing metadata updates, and titles that require accessibility remediation.

This helps the team focus on the work each book needs.

Once the status is clear, publishers can use consistent review rules for every group.

They should also record the version of the EPUB used during assessment.

If a corrected edition replaces the original, its metadata should be reviewed again.

For large collections, this approach is more reliable than making one accessibility claim across every title.

Gentize's Accessible EPUB Backlist Remediation Guide explains how publishers can plan wider accessibility improvements for older ebooks.

Who should approve EPUB accessibility metadata?

Metadata quality depends on cooperation between production and distribution teams.

The production team knows which features were included in the EPUB.

The accessibility team reviews whether those features work and meet the agreed requirements.

The metadata team prepares the package and ONIX information.

The distribution team checks that the approved record reaches the correct partners.

Each team has a different role, but they need a common source of information.

A simple approval record can help.

It may include the title, ISBN, EPUB version, accessibility review date, approved metadata, and the person responsible for final sign-off.

This makes future updates easier to manage.

It also reduces the risk of distributing an older record by mistake.

How should publishers update metadata after a new EPUB release?

An EPUB can change after its first publication.

A publisher may correct navigation, add descriptions for charts, or improve support for reading tools.

These changes can affect its accessibility metadata.

For example, a title may originally have limited image descriptions.

After a remediation project, those descriptions may become available throughout the book.

The publisher should review the new file and update the metadata to reflect the change.

The same applies when a new edition introduces interactive content or different navigation features.

Version control is important.

Teams should know which accessibility statements belong to each released file.

A simple update process helps keep product information accurate over time.

How can publishers measure metadata quality?

Metadata quality is not only about the number of fields completed.

A record can be complete but still contain incorrect claims.

A better review looks at three areas.

The first is coverage. Does every relevant title contain the required accessibility information?

The second is accuracy. Do the statements match the approved publication?

The third is consistency. Does the ONIX record communicate information that agrees with the EPUB?

Publishers can also track how often metadata requires correction after release.

Frequent corrections may reveal gaps between production, accessibility testing, and metadata approval.

These measures help teams improve their process without adding unnecessary reporting work.

How Gentize supports EPUB accessibility metadata

Gentize Innovations supports publishers with accessible EPUB production, remediation, accessibility metadata, and quality assurance.

Its accessibility services include structured content, navigation, alternative text, accessible tables, metadata review, and assistive-technology testing.

Gentize also has 50+ accessibility testers with visual impairments who support human-led accessibility QA.

Its publishing experience includes a 35,000+ title academic digitization project covering scanning, OCR, EPUB, POD, and accessible PDF.

A stronger production team supports larger publishing programmes, while specialist reviewers help assess complex content.

Gentize can also support projects where older EPUB files need accessibility improvements before their metadata can be updated.

For publishers managing many titles, a representative sample can help identify missing features, metadata gaps, and the work required.

Final thoughts

EPUB accessibility metadata helps readers understand how they can use a digital book.

It also helps publishers share accurate accessibility information with retailers, libraries, and distribution partners.

The most important rule is simple: metadata should describe the finished ebook, not the features that were only planned.

Publishers should review the EPUB, confirm its accessibility features, update the ONIX record, and approve both before distribution.

A clear process helps maintain accurate records across new releases and older catalogues.

For readers, the result is better information about the ebooks they choose.

For publishers, it is a more reliable way to manage accessible digital content.

Need EPUB accessibility and metadata support?

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