Thema Implementation: Practical Considerations

Related Pages

Thema Subject Codes
Thema Basics: Subject Categories, Qualifier Codes, National Qualifier Lists
Thema ONIX Sample
BISAC to Thema Translator 

What needs to be recorded in a dataset – basic guidelines for developers

What does your inhouse system or ONIX-specific software need to support Thema?  This is an outline and you must consult the full ONIX Specifications and Best Practices as well as the North American Best Practices for business rules around the support.  I'm restricting this to North America practice, but please note: BIC is transitioning their subject system to Thema so confirm with your trading partners if you need to continue to support BIC.

A Main Subject

One of the Thema Subject category codes and one of the BISAC Subject Codes is designated as a Main Subject.  All other subject and related codes list here appear as a "regular" subject.  See Thema ONIX Sample for a fuller explanation.

ONIX Code List support for List 26 Subject Scheme Identifier

Within North American trade publishing these are supported by most Canadian publishers:

  • Thema subject category code 93 and Thema qualifiers, codes 94 through 99
  • BISAC subject heading code 10, BISAC regional code 11 and BISAC merchandising code 22
  • Keywords code 20

ONIX 2.1 software needs to

  • Support for both the “Main Subject” composite (ONIX Code List 27 -- with identical numbering in these sections as List 26 above) and the “Additional Subject” composite (ONIX Code List 26)
  • Allow for at least two instances of Main Subject to provide support both Thema and BISAC 
  • Allow for multiple instances of the Additional Subject composite. 
    • For complete coding Thema may need to support two codes values where one will do in BISAC.
    • Supporting both systems may means the ONIX 2.1 <Subject> composite might need to support as many 10 <Subject> composites in addition to any other need like Keywords.

While BASICMainSubject element is provided for BISAC (and there one for BIC main subject as well) there is no unique ONIX 2.1 element to support a Thema Main Subject.  Your only option is to use the Main Subject composite.  Your trading partners may prefer to load all their data from the Main Subject composite, so you should consider supporting BISAC within the Main Subject composite. The safest course would be to provide an identical BISAC main subject in both BASICMainSubject and within a Main Subject compost MainSubjectSchemeIdentifier=10 (BISAC Subject).  

You should always check with main trading partners to ensure that they can support any changes you're making to the data.

ONIX 3.0 software  

ONIX 3.0 is a simpler implementation in that the Subject composite is the only one used.  Main Subjects are identified by including an extra empty set <MainSubject/> tag within the composite.  The only point to stress might be that

  • being able to support multiple instances of the Subject composite is required
  • and you need to support the <MainSubject/> empty set tag appropriately.

Transitioning to Thema

The BISAC to Thema Translator can provide a start on Thema codes for backlist titles, but it’s most important for publishers to familiarize themselves with the Thema Subject list and start applying values from this list to their bibliographic records. The next step is to supplement the Subject list values from the Qualifier lists as necessary.

It is important to take the time to learn how to use the lists in a way that will give retailers the information they need to maximize sales. This means using codes with focus—some might say sparingly, but always effectively.

We have to recommend that run Thema and BISAC subject lists at the same time.  The US market will likely remain BISAC driven indefinitely and Canadian retailers still use that system.  If you run into problems with the system or conflicts with retailers over your usage of the system, let us know at

Remember, at this stage there’s no right or wrong way to implement Thema — just expected use and talking to trading partners is the best source.

Avoiding duplication with ONIX

BookNet Canada strongly encourages publishers and retailers to continue to use and support the current ONIX structures for Audience, and to use Audience Ranges to support Education values for North America.

Certain values in the Thema lists will appear similar to ONIX values in other fields. If you feel you are simply duplicating values in Thema that you’ve already supplied in your ONIX metadata, that is a good reason to question whether you need to be adding these details in Thema at all. 

Example: ONIX "Year of Annual" vs. Thema Time Period Qualifier

Consider a book titled Canadian History Yearbook 2014. The content essays would be set in any number of Time Periods. The year of the annual’s publication (2014) is not a subject—it’s just the year the research was compiled into a single volume.  This value should already be supplied in your metadata, using the “Year of Annual” ONIX element.

If this volume concentrated on a certain time period (1830–1850, for example), then that would be a subject.

That's relatively clear to see in this example, but it's just as true for the Sociology Yearbook 2014.  The clue here is you've already supplied 2014 as part of the bibliographic metadata.

Example: ONIX "Language of Text" vs. Thema Language Qualifier

The ONIX Language of Text field and the Thema Language Qualifier both require a little effort to understand, but when you get a firm grasp on them you will find the two systems support each other, allowing you to supply clear language information to retailers.

In ONIX, Language of Text doesn't actually refer to the language the book is written in.  Instead, it identifies the language of the reader—the intended language market.  Generally, these values are identical. But consider a book written partially or entirely in French that is intended for use in language instruction. In ONIX the Language of Text is set as English, not French, allowing retailers selling to an English-language market to identify the book as appropriate for their market.

The Thema Language Qualifier works in a different way. The language a book is written in is never a subject on its own, even if this is a major selling point of the book. A book may feature dialogue written in Quebecois or Jamaican Creole, but that is not actually a subject of the book.  The ONIX Language of Text would still be based on what language group the retailer is selling to – likely French in the former or English in the latter, and it would be up to the marketing and descriptive copy to highlight use of dialect as a feature of the book. 

But consider a French-language book whose intended audience is English-speakers learning the French language. The ONIX Language of Text (English) tells the retailer which market the book is intended for, and the Thema Language Qualifier (French), plus a Subject code from “Language teaching & learning group,” allows the retailer to place the book properly within their store or system.

Of course, any time a book is about a language—say, the history or etymology of French—then a Thema Language Qualifier would always be used regardless of what language the book was written or sold to.  

Qualifiers are exactly that:  They don't define the book's subject, they provide additional information about the subjects used.  The subject code would define the difference between a language instruction text and a history of language book.  The Qualifier adds the language.