Doing Research at the Library of Congress

IIA. Three Basic Principles of Library of Congress Subject Headings

b. Scope-match level of coverage

The principle of scope-match coverage refers to the level of depth at which books are indexed. As a rule, catalogers try to assign only as many headings to a work as are necessary to sum up the subject of the work as a whole. In other words, they will not usually assign headings for each individual chapter or section of a book. The result is that most catalog records receive from two to five headings rather than ten or fifteen, and many books receive fewer than three. For example, a book covering Oranges, Grapefruit, and Tangerine will receive these three headings; but if it also covers Lemon, Limes, and Tangelo it will receive the one heading Citrus rather than six individual terms at the chapter-level. The level of depth aimed for is the smallest number of headings covering the book as a whole. (Note that chapter titles are sometimes transcribed as keywords within the "note" fields of catalog records; but this level of indexing is not covered by the standardized terms of the subject headings system.)