Library and Archives Canada assigns subject headings to titles selected for "Full" level treatment for listing in the national bibliography Canadiana.
LAC aligns its subject cataloguing practices as closely as possible with that of the Library of Congress, while exercising discretion to meet the needs of Canadian users.
LAC assigns subject headings drawn from the following standard lists:
- Library of Congress Subject Headings (LCSH), for English headings;
- Canadian Subject Headings (CSH), for English headings, where Canadian requirements are different from or are not reflected in LCSH policy or practice; and
- Répertoire de vedettes-matière (RVM), for French headings.
Unilingual publications are usually assigned subject headings in both official languages. Cataloguing-in-Publication (CIP) records created for titles before publication receive subject headings in one language only, depending on the language of the publication, and are upgraded with bilingual subject headings once the title is published.
For bilingual publications, where two complete bibliographic records are created, one in English and the other in French, English subject headings are added to the English record and French headings to the French record.
Assigning subject headings
LAC cataloguers assign the most specific and up-to-date heading or headings appropriate to the subject of the work catalogued. New headings may be established for CSH or proposed for addition to LCSH where necessary.
Name and uniform title headings used as subject headings are assigned in accordance with AACR2.
- Extremely specific topics - LAC assigns two or more headings in place of a single heading for extremely specific topics.
- Complex topics - LAC assigns headings for two or more individual aspects of complex topics, relying on postcoordination on the part of the user when searching for the topic.
- Multiple topics - Rule of 3 - LAC normally applies the rule of three for multiple topics. Separate headings are assigned for up to three similar topics but for four or more topics, a single broader heading is assigned.
- Subtopics and Secondary topics - Subtopics of special emphasis or secondary topics not related to the main topic are brought out using extra subject headings if they make up at least 20 percent of the work catalogued.
The extra heading(s) are omitted if:
- substantial extra work would be needed to determine whether the topic makes up 20 percent of the work in hand;
- substantial extra work would be needed to determine what heading or headings should be assigned;
- the treatment of the topic in the work is not of sufficient importance to Canadian library users to merit special treatment;
- a Canadian library user seeking works on this topic would probably not be satisfied with the work in hand.
- Subordinate aspects of a topic - Extra headings are also assigned to bring out important subordinate aspects of the topic in certain subject areas such as local history, genealogy and biography.