ONIX for Books is the XML metadata standard maintained by EDItEUR, the international body that governs book-trade standards. It is the format retailers, wholesalers, aggregators and libraries expect when they receive information about a title: identifiers, titles, contributors, descriptions, subjects, prices and availability all travel in one structured message.
This guide walks through the shape of an ONIX 3 record and the mistakes that get feeds rejected, in language meant for editors rather than engineers. And if you would rather not write XML, Origami can build the record for you from the EPUB you already have.
What ONIX for Books is — and why version 3
ONIX is the common language of the book supply chain: instead of filling in each store’s form by hand, you send one structured record and every system reads it the same way. It is maintained by EDItEUR, together with the code lists that give each field a controlled set of values.
The current version is ONIX 3.0 (with the compatible 3.1 revision). The older ONIX 2.1 stopped being maintained at the end of 2014, and many trading partners now reject or ignore 2.1 feeds. If a system still exports 2.1, treat it as technical debt to retire, not a working setup.
The building blocks of an ONIX record
An ONIX 3 product record is organised into blocks. You do not need to memorise the tag names, but knowing what lives where helps you spot gaps.
Identifiers come first. Every commercial edition needs its own ISBN-13 (also expressible as a GTIN-13), plus a product form code that says whether it is an EPUB, a paperback or an audiobook. A different format is a different product: the EPUB and the print edition carry different ISBNs.
The descriptive block carries the title (in TitleDetail, which separates the title proper from the subtitle), the contributors, the language and the extent (page count or duration). Each Contributor is tagged with a role from EDItEUR List 17 — for example A01 for author, B06 for translator or A12 for illustrator — so a store can label the person correctly.
Marketing copy lives in the CollateralDetail block: the main description, short blurbs, review quotes and cover images. This is the text that becomes the product page, so it earns real sales, not just compliance.
Finally, commercial terms sit in ProductSupply: availability, the supplier, and Price inside SupplyDetail, each price carrying an amount, a currency and a tax treatment. A price with no currency, or the wrong one, is one of the fastest ways to be rejected.
Subjects, audience and discoverability
Subject codes decide where your book is shelved and how it surfaces in search. ONIX lets you attach several schemes at once. In North America the dominant scheme is BISAC; the global, multilingual replacement for older national schemes is Thema, also maintained by EDItEUR. Best practice is to send both, each identified by its scheme code so the receiving system knows how to read it.
Alongside subjects, an audience code signals the intended readership — general trade, professional, or a specific age range for children’s titles. Getting this right keeps a young-adult novel out of the wrong catalogue and helps age-gating and curation.
Accessibility metadata and the EAA
Since the European Accessibility Act took effect in June 2025, accessibility information is no longer optional for ebooks sold in the EU. ONIX 3 expresses it through ProductFormFeature entries that declare features such as a navigable table of contents, described images, a logical reading order and any known limitations.
These fields let retailers show a compliant accessibility statement on the product page. If your EPUB is accessible but your ONIX record is silent about it, neither shoppers nor stores can tell — so the metadata has to say out loud what the file already does.
Common ONIX mistakes to avoid
A handful of errors account for most rejected feeds. Still sending ONIX 2.1 instead of 3.0. Missing or unqualified subject codes, so the book has no BISAC or Thema. The wrong contributor role, such as tagging a translator as the author. Price and currency problems — a missing currency, or a tax rule that does not match the market.
The last big gap is accessibility: an EPUB 3 that meets the standard but ships an ONIX record with no ProductFormFeature data. Each of these is cheap to fix at the source and expensive to chase once a distributor bounces the file.