Government of Canada
Core Subject Thesaurus

• Introduction
• Basic Rules
  • Use the Thesaurus Relational Structure to Find Descriptors
  • Choose the Most Specific Descriptor Available
  • Choose as Many Descriptors as Needed
  • Entering Descriptors
  • Contact the Thesaurus Manager

Introduction

The CST is designed to be a broad, high-level post-coordinated thesaurus. Post-coordination means that most concepts are represented by single words; compound terms are used only when there is no alternative or when that phrase is commonly used to represent that concept. Subjects to be identified and indexed are represented by one or more terms as appropriate.

For example, “Reports” can be combined with any other appropriate term ‘X’ in order to represent a report on subject ‘X’. Post co-ordination restricts the size of the vocabulary thereby facilitating maintenance and use. Boolean searching by either the searcher or the search engine will combine (“post-coordinate”) terms at the time of search.

Under TBITS 39.2, the Government of Canada Core Subject Thesaurus is the default controlled vocabulary for federal departments. “Default” means that if an alternate, authorized vocabulary is not available, then the Core Subject Thesaurus (CST) must be used as a source of indexing terms.

In any case, it is highly recommended that one or more terms from the CST be applied to <dc.subject>. The reason for this is that the CST has been developed on the basis of a number of indexing projects that extracted broad, high-level terminology used in GOC publications. Therefore, it represents the language generally used in information resources across government. By design, it does not include specialized terminology used in specific and limited disciplines.

Basic rules

Users of the GoC Core Subject Thesaurus should apply the following basic rules to ensure consistency of resource content representation within and across organizations.

1. Use the thesaurus structure to find descriptors
2. Choose the most specific descriptor available
3. Choose as many descriptors as needed
4. Entering descriptors
5. Contact the Thesaurus Manager if you have any queries

1. Use the Thesaurus Relational Structure to Find Descriptors
   
   
Browse through the alphabetical display of “lead-in” terms (labelled USE: in the full term display) and indexing terms. Then consult Broader terms (BT:), Narrower terms (NT), and Related terms (RT) attached to each descriptor (indexing term) that appear to exactly or closely represent the concept to be represented in indexing or metadata. These relationships define the meaning of a descriptor, and they suggest other index terms that may be relevant. In addition, the full record for indexing terms (descriptors) may include Scope notes (SN:) that further elucidate or restrict the meaning of the term for indexing purposes.


2. Choose the Most Specific Descriptor Available
   
   
Using “Libraries” as an example, suppose that descriptors (indexing terms) were required for a document dealing with the activities of the National Library of Canada (such as an annual report). In that case, the narrower term “National libraries” is more specific than “Libraries” and should be used instead of “Libraries”.

Note that proper names such as “National Library of Canada” are not included in the thesaurus and may not be used to populate <dc.subject>.

If the document was “about” national museums, libraries, art galleries and the like, then the Broader term “Cultural institutions” might be a better choice. Whichever term is chosen, the full term record for that term should be consulted to ensure that Broader, Narrower or Related terms within those records are not more appropriate.

It is important to bear in mind that a given term record only refers to one level up or down. A given term record does not display the narrower terms of its narrower terms.


3. Choose as Many Descriptors as Needed
   
   Use as many authorized descriptors as needed to fully describe the contents of an information resource. Subject descriptors are not mutually exclusive. More than one subject descriptor will be needed to describe most resources. For example, to index an information resource concerned with the transportation by rail or by truck of toxic waste and other dangerous products will be represented by the following set of descriptors:
   
   Dangerous products
   Hazardous waste
   Rail transport
   Road transport
   
   
4. Entering Descriptors
   
   Enter the authorized descriptor exactly as it appears in the Core Subject Thesaurus. Generally, this means that only the first letter of the first word is capitalized. In English, concrete (countable) nouns are presented in the plural form (e.g. Airports), while collective or abstract nouns are displayed in the singular form. In French, most nouns are presented in the singular form (e.g. Aéroport). These accepted thesaurus conventions and must be followed to ensure consistent use of terms.
   
   In GOC metadata, separate descriptors with a semi-colon (a semi-colon is used as a separator rather than a comma because a controlled subject term may include other punctuation marks within it). For more information on GOC metadata standards, consult TBS and the Government of Canada Metadata Implementation Guide for Web Resources, 2nd ed. http://www.nlc-bnc.ca/6/37/s37-4016-e.html
   
   One may index using either the English thesaurus (CST) or the French thesaurus (TSB). However, English terms must be applied to English language documents, French terms to French language documents and both English and French terms to bilingual documents. In some cases, there is more than one equivalent term in the other language. For example, the English term “Education” has two equivalents in French, “Éducation” and “Enseignement” which are displayed in the term record separated by a slash (“/” ) as follows:
   
   

   Education

   FRENCH:

   Éducation / Enseignement

   The indexer must be careful to select the correct and appropriate term for the French document.
   
   
5. Contact the Thesaurus Manager
   
   If you have any questions about the thesaurus please contact the Thesaurus Manager. This includes general queries, additional information about thesauri and their use and suggestions either for new terms or for changes to existing terms.