Rules
Part of Ebook marketing: what to keep and what to drop for 2027
Ebook marketing claims about format: what to test first
Ebook marketing claims about format, checked before they reach a listing: what EPUB 3.3 covers, accessibility metadata, rich-feature fallbacks and app tests.
What to take away
- EPUB 3.3 is a format standard, not a promise about every reading system.
- Advertise accessibility only as far as the file's metadata and a check support.
- Treat audio sync, scripting and other rich features as optional layers with a fallback.
- Name a format in a listing only after testing it on the devices buyers use.
Format is where many ebook marketing trends turn into claims on a product page. Each claim needs a test behind it. A listing built for ebook marketing stays honest when it says only what the file does on the buyer's chosen device and app.
What EPUB 3.3 standardizes
The W3C EPUB 3.3 Recommendation, published May 25, 2023, defines a distribution and interchange format built from structured web content. It also links the core format with the reading-system and accessibility specifications that sit around it.
The W3C specification describes representing, packaging and encoding structured web content, including HTML, CSS, SVG and other resources, in a single-file container. That is a statement about the file. It does not establish that every reader, store or conversion tool supports every feature in it.
The Library of Congress format description lists synchronization of audio and text among the functions EPUB 3 supports. Read-along is therefore a real format capability. Whether a given app plays it is a separate question that only a test answers.
Accessibility metadata readers can find
Publish an accessibility claim only as far as it has been verified. W3C's EPUB Accessibility 1.1 and WCAG 2.2 are the references to consult, and EPUB format support alone does not establish conformance.
EPUB Accessibility 1.1 asks for discovery metadata in the package file, using schema.org accessibility properties, so that a store or library can show what a title offers. A reader who needs those features can then find them before buying or borrowing.
The listing should repeat only features that the metadata and a check confirm. Legal duties for US sellers sit elsewhere, and the guide to ADA and state accessibility rules covers them.
Rich features need a fallback
Rich media and scripting can add value for a defined book. They can also raise file size, security review, accessibility work and platform variance. Offer them as a layer on top of a book that still reads without them.
| Feature | What a listing may say | Pass only if | Fallback |
|---|---|---|---|
| Audio and text sync | Read-along edition | Audio and highlighted text stay in step in every named app | Plain text reading |
| Scripting | Interactive exercises | The exercises run in every named reader and pass your security review | Static version of the exercise |
| Embedded media | Video or animation inside the book | The media plays and the larger file still downloads and delivers normally | Still image with caption |
| Modular release | A smaller part for a narrower need | A buyer can tell from the edition name which part it is | Full edition with total price stated |
| Accessibility metadata | Features available to readers | Each listed feature appears in the package metadata and works in the file | Claim nothing unverified |
A modular release can improve fit for a reader who needs only one part. It fails when buyers cannot tell which edition they are getting or what the parts cost together.
Test the file on real reading systems
Testing each release against real reading systems is one of the ebook marketing best practices that prevents refunds and bad reviews. Standards say what a file may contain. Only a test shows what a reader displays.
- List the reading systems and apps your audience actually uses, for example Apple Books, Kobo, Google Play Books or Thorium Reader.
- Validate the file with an EPUB checker such as EPUBCheck before each release.
- Open the release on every listed system and record what renders and what breaks.
- Switch off each rich feature and confirm the book still reads.
- Write the listing from these results, naming only formats and features that passed.
Conversion and checking software varies in what it handles. The review of ebook marketing tools shows how to judge those tools before you rely on them.
Distributors check claims too
Each distributor sets its own upload rules, so a claim that passes on a reading app can still need a disclosure at the store. Amazon KDP, for example, asks publishers to disclose AI-generated text, images and translations. Check the current requirements at upload, and distinguish AI-generated from AI-assisted content.
Keep the evidence beside the claim
Label each format item as shipped, limited release, preview, announced or inferred. Name the affected workflow, the source, the owner, the test and the rollback condition. A reviewer should be able to reproduce the reasoning without relying on memory.
Recheck the primary page before you publish and again before you adopt a feature. A current release can support a planning signal. It cannot support a guaranteed 2027 capability, price, adoption rate or business outcome.
Measure what a format change does with source-tagged traffic, retailer orders, conversion or read-through where available, and the defects and support requests that follow.
Common questions
Is EPUB 3.3 required everywhere?
No. Check each distributor and reading system, then select and test formats for the actual audience.
Does a valid EPUB file count as accessible?
No. EPUB format support alone does not establish conformance. Consult EPUB Accessibility 1.1 and WCAG 2.2, then verify the file.
Which format feature should a publisher adopt first?
The one that solves a verified reader or operating problem and passes a small end-to-end test. More answers sit in the common ebook marketing questions.
