Thema is the global subject classification system used in the international book trade to categorise books by subject and audience. This article explains what Thema is, how it is used on TitlePage, and how publishers can include Thema subject codes in their ONIX metadata.
Who this is for
This information is intended for publisher staff who:
- Supply ONIX metadata to TitlePage.
- Manage subject classification for titles.
- Want to understand how Thema works on TitlePage.
Overview
Thema is a global and multilingual subject classification scheme for books and ebooks used throughout the book industry. It provides a consistent way to categorise books based on their subject matter, helping booksellers, libraries, and readers discover relevant titles.
Thema is designed to replace national subject schemes used by the book trade, providing a common classification system that works across international markets while still supporting local needs.
The system is maintained by the international standards organisation EDItEUR and is updated regularly with new categories and qualifiers to reflect changes in publishing and reader interests.
Thema on TitlePage
TitlePage supports the use of Thema subject codes within publisher ONIX metadata. As part of the industry transition away from the BIC subject classification scheme, TitlePage has made Thema the primary subject classification used for searching and organising titles.
To support this transition, TitlePage automatically translates BIC subject codes to equivalent Thema codes when records are received without native Thema classifications. This allows publishers and booksellers to begin working with Thema while maintaining compatibility with existing metadata workflows.
Why Thema matters
Accurate subject classification improves discoverability for booksellers and readers. Using Thema allows publishers to describe books more precisely, including subject matter, audience, and geographic context. Better metadata helps retailers, search systems, and recommendation tools connect readers with relevant titles.
Subject classification is one of the core metadata fields measured in your weekly Data Quality Report. See Data Quality Reports.
Providing Thema in ONIX
Thema codes are supplied in ONIX metadata within the Subject composite. Publishers may include:
- A primary Thema subject code describing the main subject of the book.
- Additional Thema subject codes to provide more detailed categorisation.
- Qualifiers that add further context such as geographical setting, audience, or theme.
Providing accurate and complete Thema metadata helps ensure titles appear in the correct subject categories on retail systems and discovery tools. For the codelist version TitlePage supports, see ONIX Versions, requirements, codelists.
BIC to Thema translation
Many legacy publishing systems still use BIC subject codes. TitlePage supports this transition by automatically mapping BIC codes to their equivalent Thema classifications when Thema is not provided.
Mapping is not always precise, so supplying native Thema codes gives you more control over how your titles are categorised and discovered.
Publishers are encouraged to begin supplying native Thema codes in their ONIX metadata as Thema becomes the primary classification system used by the industry. More information about the TitlePage Thema transition can be found on the APA website.
Further resources
Official Thema resources and documentation are available from EDItEUR:
You can also refer to the APA Thema resources for additional guidance, training material, and training courses.
Related articles
- Metadata Best Practices, including First Nations subject codes
- ONIX Versions, requirements, codelists, the versions and codelists TitlePage supports
- Interpreting my Data Quality Report, how subject data affects your score
For further information please contact TitlePage support.