Thesaurus for Graphic Materials I: Subject Terms (TGM I)
INTRODUCTION (1995 printed edition)

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II. Indexing Images: Some Principles

II.D. Generic and Specific

TGM I terms should be applied following the principle of "specificity," which requires that the most specific term possible be used to describe a subject. That is, an image of a rose is indexed under Roses, not under the broader term Flowers, and not under both terms.

When an image is indexed under a proper name heading, however, both the name heading and a generic subject term can be applied. For example, Department of the Interior Building (Washington, D.C.) and Government facilities; Knights Templar (Masonic order) and Fraternal organizations; Langtry, Lillie, 1853-1929, and Actresses. This double indexing practice is useful because, while for some types of research, picture searchers seek names of specific people, places, and things, for other types of research, they want generic examples of a subject (i.e., not a particular named example) to illustrate a concept. It would be asking a lot to expect researchers to think of the names of all organizations, actresses, or government buildings that might be represented. Indexing for both generic topics and specific instances is the most satisfactory solution to this problem.

Unfortunately, always indexing under both generic and specific instances of a subject can become highly impractical, particularly when a catalog record requires many subject headings, or when an institution can ill afford the expense of authority work necessary to establish headings for proper names. Responding to the questions posed in Section II.A. and II.B. may help a cataloger decide where to economize in the assignment of headings. That is, rather than automatically assigning both generic and specific headings in every case, the usefulness of each should be evaluated in advance; only those headings which provide access to the most significant characteristics of images being cataloged should be assigned.

When double indexing October 22, 2010 in which there are often cross references between generic topics and named instances (e.g., Holidays see also Arbor Day), may compensate and guide users among generic and specific terms.

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