Thema: The Subject Category Scheme for the Global Book Trade

In the book trade one important aspect of the marketing of books to potential clients is giving accurate information about the subject or genre of the book in question. This has been done by publishers, librarians and booksellers over the years. Publishers will create catalogues or marketing material showing the subject. Librarians will follow clear and precise cataloguing rules to attribute subject codes to the titles in their collections. Booksellers will place titles in subject sections to help clients find the titles. 

With the growth of EDI (Electronic Data Interchange) various book trade schemes were developed to provide standard subject headings and codes, to allow for easy identification of subjects and tracking of sales statistics. 

© Tom Gauld

© Tom Gauld

These schemes were usually created by national bodies, such as the BIC subject scheme launched in 1997 in the UK or the BISAC codes created for the US market in 1995. There are equivalents to these schemes in many countries. Since then there has been an explosion in online resellers and digital versions of content. There is more and more content available to a greater number of consumers in an increasingly global market. 

The growth of this global market has been the background to creation of the standard message format to transmit book metadata in the global book supply chain, ONIX. This standard allows publishers to communicate the same information to any trade partner anywhere in the world. However, a publisher trading in multiple markets and with retail clients who also trade in many countries would have to send various codes from various book trade subject schemes. The BIC code for the UK, BISAC for the US, CLIL for France, NUR for the Netherlands, WGS for Germany and so on. The relevant code list in ONIX (list 27) of recognised subject schemes is one of the longest. This is a lot of work for publishers, data aggregators or retailers. Often, they create mappings from the schemes to their own scheme or to a principle one. This however means a lot of mapping and potential for loss of detail or confusion. 

The need to reduce the duplication of work where more than one scheme is in use and the elimination of the costly and imprecise mapping process was the background for the idea that the international book trade needed a standard scheme to simplify the communication of the subject codes around the globe. The initial idea was an attempt to ‘internationalise’ BIC, which is very British and orientated towards the UK book trade. Modified versions of BIC were being used in Spain, Italy and other countries and during 2011 and early 2012, a proposal for a more internationally-balanced version of the BIC scheme named IBIC emerged. IBIC itself was never released but it led to the formation of a much larger group of stakeholders, including the BISG from the USA and BookNet Canada, who were willing to work on a global scheme that ultimately became Thema. 

The goal was to create a scheme that was multi-cultural and multi-lingual, applicable to all parts of the book supply chain and flexible enough to allow each market to retain its unique cultural voice, while remaining a unified and simple-to-adopt scheme. It was, and still is, suitable to be used alongside existing national schemes. Thema has a governance structure where it is managed and maintained by EDItEUR, who also manage the ONIX standard. There are a number of national or regional interest groups who represent the interests of their markets and who send representatives to the Thema International Steering Committee who make suggestions and decisions about the development of Thema ensuring it remains global and relevant. 

Thema has a hierarchy of subjects. There are 20 top level categories, each subdivide into many sub-categories. Each of these has an alphanumeric code and an associate d heading. In some cases, they may also have an associated note. There are about 3000 of these subject headings. The hierarchy implies that books should be classified to the most detailed appropriate level (not necessarily the most detailed possible level), and a book classified as – for example – AGA (History of art) is also automatically and more generally associated with the AG (Fine arts: treatments & subjects) and A (The arts) categories. The headings have been translated into about 20 languages so far. The codes can be transmitted to any partner without the meaning of the category changing. 

In addition to the headings, there are post-coordinated ‘qualifiers’ that can be used to refine the meaning of the main subject categories. There are 6 of these qualifier types: 

  1. Places- where the book is about or takes place 
  2. Language- the language the book is about and not the language the book is in. 
  3. The time period the book is about, or the action takes place in 
  4. Educational level qualifier- the grade, exam, type of education etc. 
  5. Interest qualifier gives an idea of a group that may be interested by this title, eg 15 years old and up, African-Americans, Buddhists, Lesbians etc. 
  6. Style qualifiers- which are used with the arts subjects mainly

Finally, there are ‘national extensions’ within the qualifiers. These are a very important part of Thema and allow for a local feel to a global scheme. The extension codes are arranged so that national extensions can be truncated to leave a meaningful ‘global level’ qualifier if the national extension is too specific. 

The way that Thema works allows meaning to be built up by using one or more subject codes plus qualifiers and this ensemble carries the ‘subject’ of the book. 

Subject classification provides the core context within which other search strategies can be used. It may not be visible to the end user, but it underpins the search and retrieval logic. The basic function of any subject scheme is to provide a key access point for research and discovery for consumers, to enrich product information between trading partners, to inform purchasing decisions, to enable a common language for sales reporting, to identify trends and so on. Thema provides these things on a global level.

For more information about Thema click here and to see the Thema subject codes click here.