Thema

This matters mainly if your book will be sold outside the United States and Canada, because a book carrying only North American subject codes may be poorly categorized, or not categorized at all, in a market whose retailers read this scheme instead. If you sell only at home, there is nothing here for you to do. Traditionally and hybrid published authors normally ask whether Thema codes are assigned and what they are; if you publish the book yourself, you check whether your platform offers a Thema field, and some do not, in which case there is nothing to fill in. Find out whether Thema codes are assigned and review them if they are.

Thema is the international subject category scheme for books, maintained by EDItEUR, the same body that maintains ONIX (ONline Information eXchange) for Books. It uses alphanumeric codes across twenty-one top-level subject areas plus six sets of qualifiers for place, language, time period, educational purpose, interest age, and style. Version 1.6 was current when this record was checked.

Thema was designed so that one set of codes could work across countries and languages. Publishers outside North America generally use it as their primary scheme, and many North American publishers send both BISAC and Thema codes in their metadata.

How a book is categorized in markets and systems that read Thema rather than BISAC, which includes most European and many other international retailers and wholesalers. Like BISAC, the codes travel inside the ONIX feed. A book with only BISAC codes may be poorly categorized, or not categorized at all, in a Thema-first market.

This matters mainly when the book will be sold outside the United States and Canada. Ask whether Thema codes are assigned and what they are; browse the scheme on the EDItEUR site to check that they describe the book accurately. The scheme is free to browse.

If the publisher or distributor does not assign Thema codes and international sales matter to you, ask whether they can. Self-publishers should look for a Thema field in their platform and fill it in with the same care as the BISAC codes.

1. Ask the publisher or distributor whether Thema codes are in the metadata and request the list.
2. Look each code up in the Thema browser on ns.editeur.org (opens in a new tab) to confirm it exists in the current version and fits the book.
3. Check the book's categories on an international retailer where it is sold.
4. Send corrections to the feed owner, not the retailer.

Thema is not BISAC, although the two are mapped to each other and a book can carry both. It is not a keyword list and not a library classification. EDItEUR also maintains ONIX, but Thema is a code list that rides inside ONIX, not a feed.