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| Thesauri & controlled vocabularies |
Thesauri and Controlled VocabulariesImplementing Controlled Vocabulary on Government of Canada Web SitesFrequently Asked Questions
What is a controlled vocabulary?A controlled vocabulary is an established list of standardized terminology for use in indexing and retrieval of information. An example of a controlled vocabulary is subject headings used to describe library resources. A controlled vocabulary ensures that a subject will be described using the same preferred term each time it is indexed, making it easier to find all information about a specific topic during the search process (e.g., Canadian Subject Headings, www.collectionscanada.ca/csh/index-e.html or the Répertoire de vedettes-matière (RVM), www.collectionscanada.ca/rvm/index-e.html) See more definitions related to standardized terminology on the Definitions page. 
Who uses a controlled vocabulary and who decides on the terms?Content creators use terms from a controlled vocabulary to describe the information contained in their documents. As a result, Canadians have quicker, focused access to the government information they need. Preferred terms are terms selected from amongst a group of synonyms to be the authorized descriptor. Searchers use controlled vocabularies by selecting terms from a thesaurus or list of preferred terms, then searching websites or databases for those terms that suit their information needs. Specialists, such as librarians, make decisions about which terms should be designated as “preferred” in a controlled vocabulary. To do this, they look at the terminology used in the information resources. They also consult with other specialists and researchers working in the subject field. Preferred terms will be the ones most commonly used in the discipline. Not all situations call for using controlled vocabulary. It is labour-intensive and time-consuming to develop a controlled vocabulary system. Controlled vocabulary is most valuable for scholarly or technical materials that result from extensive research.
Why use a controlled vocabulary?Assigning terms from a controlled vocabulary facilitates access to government information for all Canadians by allowing focusing of search results on Government of Canada search engines. For further information, consult the Metadata Implementation Guide at:
What controlled vocabulary do I use?The Common Look and Feel (CLF) Standard for Government of Canada Internet sites requires that terminology from a controlled vocabulary or formal classification scheme be used as values in the "dc.subject" metatag describing Web resources. According to TBITS 39.2, the controlled vocabulary used must be recognized by the Dublin Core Metadata Initiative (DCMI) or be registered with the National Library of Canada. More specifically, the standard adopts the Government of Canada Core Subject Thesaurus (CST) from the Depository Services Program (DSP) - http://en.thesaurus.gc.ca/these/thes_e.html - as the authorized thesaurus to be used by federal organizations. Consult your departmental library and information management experts to determine if a controlled vocabulary or formal classification scheme is already in use in your department. The default vocabulary, if no departmental scheme is available, is the Government of Canada Core Subject Thesaurus (CST). In any case, for interoperability purposes, it is highly recommended that one or more terms from the CST be selected as the content for "dc.subject". Other registered vocabularies and/or classification schemes may additionally be used. If the terms you need to describe your information are not
in the CST, or if your subject area is not well represented,
please contact the Government of Canada’s Thesaurus Manager using the form
at: If the terminology of the CST is too broad or otherwise unsuitable for use as descriptors for your information, consider using a different controlled vocabulary. Consult the advice in the Metadata Implementation Guide - Managers' section on the Council fo Federal Libraries' site (www.collectionscanada.ca/cfl-cbgf/s37-4016-e.html) If all else fails, consult the Metadata Coordinator at the National Library of Canada for advice. E-mail: meta_coord@lac-bac.gc.ca.
How do I implement controlled vocabulary on our Web site?Consult the Indexing Federal Government Web Pages:
Guidelines For the Development of an Indexing Policy page
for general implementation advice. (www.cio-dpi.gc.ca/im-gi/meta/index/ If you will be using the CST, see the Web page Guidelines for the Use of the Government of Canada Core Subject Thesaurus for Indexing on the CST site: http://en.thesaurus.gc.ca/guide_e.html
Which Web pages are involved?Guidance on how to identify key departmental resources for the purposes of meta tagging is available in the TBITS Metadata Standard (39.1):
Where can I find more information on controlled vocabularies?See the Thesauri and Controlled Vocabularies section of the National Library Web site
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