Licensing a Taxonomy or Ontology

Posted on: December 04, 2018, by: Ann Kelly

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Taxonomies, thesauri, or ontologies should be custom designed for each implementation, taking into consideration the unique set of content and the users. Nevertheless, there are situations when licensing a taxonomy or ontology created by a third party may be desirable, such as for a start of a taxonomy/ontology that is then modified, for a single facet of a faceted taxonomy, or for tagging multi-source research content.

Taking an existing taxonomy/ontology created by a third party without modification can have several problems. Its scope may be slightly narrower or it might not be as detailed, so needed concepts would be missing. Its scope may be slightly broader or it may be more detailed than needed, so it’s cumbersome and not user-friendly, and indexing with it would be inconsistent. Its language style might not suit the new users, so users cannot find what they are looking for. Its terms and even their alternative labels (synonyms), may not match the language of the content, so content may not get indexed properly. Finally, it might not even have the desired structure, such as the difference between a hierarchical taxonomy, thesaurus, or ontology.

Licensing Uses

Licensing a taxonomy/ontology can be done as a starting point, which can thus be sufficiently modified for its new use. Modifications include removing concepts out of scope and not needed, adding missing concepts and their relationships, creating additional alternative labels to existing or new concepts, and changing the wording of selected preferred labels to conform with the preference of the users. If only a fraction of concepts need changing, and it’s more a matter of adding new concepts, then licensing can be a good way to get a taxonomy/ontology up and running much more quickly than starting from scratch.

Licensing a taxonomy/ontology to serve for just one or two facets or metadata properties of a larger taxonomy/ontology set may also be a practical option. A faceted taxonomy enables a user to filter or limit search results by a combination of concepts selected from multiple facets/filters. For example, for images, these could be a geographic place, location type, occasion, person type, time of year, activity, and an object. It might be desirable to license a taxonomy/ontology for a geographic place or person type and create the other vocabularies. Other examples of a single-facet taxonomy/ontology that might be of interest for licensing include product types and industries.

Licensing a taxonomy/ontology as is, with little or no modification, is sometimes appropriate if the original purpose and the new purpose are the same and the type of user is the same. This would not be the case for internally created content, but if the content comes from multiple external sources, such as published articles, and the users are conducting external research, then a third-party created taxonomy/ontology in the desired discipline or industry might be appropriate. Fields such as medicine, pharmaceuticals, engineering, and the sciences, in general, may be suitable for licensing a taxonomy/ontology.

Licensing Issues

The licensed taxonomy/ontology not only needs to be in the appropriate subject area but needs to have been initially created for a similar audience and purpose, which can be determined by contacting the original creator/publisher of the taxonomy/ontology. For example, a subject area of “finance” will have somewhat different concepts depending on whether it was created for academic/research use or for internal enterprise content management use.

The licensed taxonomy/ontology should be of the desired type: classification system, taxonomy, thesaurus, ontology, etc. This is not always obvious, since the distinctions between taxonomies, thesauri, and ontologies can be blurred, and the term “taxonomy” is sometimes used for many different kinds. So, it’s important to ask the taxonomy/ontology publisher specific questions, such as how many top terms there are, what kinds of relationships there are between concepts, and whether there are classes or categories assigned to concepts.

If modification is going to be done, which is often the case, the license needs to permit modification. An open source and free taxonomy/ontology may restrict modification and require attribution to the source of the unaltered taxonomy/ontology. An open source and free taxonomy/ontology will typically not allow commercial reuse either. A paid license typically permits
modification and commercial reuse.

A taxonomy/ontology that is available for license typically comes in standard interchangeable formats, such as CSV, RDF/SKOS, or RDF/OWL, so it can be imported into ontology management software, such as Semaphore Ontology Editor, where it can be further modified. An understanding of the formats is needed to select the most desirable one when multiple formats are supported.

Licensing Sources

Finding the right taxonomy/ontology is important. There is a relatively new international resource, developed and maintained by the University of Basel Library, the Basel Register of Thesauri, Ontologies & Classifications (BARTOC). Each taxonomy/ontology is classified and assigned metadata for subject, category, taxonomy/ontology type, file format, language, and license type, among other classifications. It’s quite comprehensive for open source/free vocabularies, and has some, but is not as inclusive yet of commercially licensed vocabularies, but it’s growing.

Some major information publishers who have developed extensive thesauri or taxonomies to index their published content do offer the vocabularies for license, but they do not promote it, so this is little known, and they reserve the right not to license vocabularies to a party considered a competitor. Examples include the Gale Subject Thesaurus and the Associated Press’ News Taxonomy.

Licensing Trends; a Survey

To what extent do organizations seek to license a taxonomy/ontology as part of their knowledge or content management strategy? We have created a short multiple-choice questionnaire. Please take a few minutes (3-4) to fill out the Taxonomy Licensing Interest Survey.