Subject headings serve the same purpose, except that they keep entries providing access t the items together inn an alphabetical bibliographic arrangement. The first step in subject analysis of an item is to eliminate peripheral material from consideration. Specificity of treatment does not depend on the holdings of material in a particular area. Generally, the classification for an item should not be narrower than the primary subject heading. Subject analysis of a work is made based on usefulness and content, not aesthetics.
Subject analysis is based on what an item is as opposed to what it says it is.
However, try not to defy the author or publisher in assessing the purpose of a publication. For materials where judgment of subject content is especially difficult, give publisher's intent special emphasis in classification. Every map of an identifiable place must have a subject heading for the area. Maps of places that cannot be identified receive no geographic subject headings. There is no limit imposed on the number of subject headings that can be given to a particular item for full-level cataloging, provided they are properly applied.