b'The Purpose of Subject Catalogingspelled out in the NISO Guidelines for the Construction, Format, and Management of MonolingualThesauri. A subject heading list, such as the Sears List or the Library of Congress Subject Headings,is simply an alphabetical list of terms that have been established over time as warranted by thematerials being cataloged. Asubject heading list also indicates relationships among terms but doesnot attempt to establish any comprehensive hierarchies. In addition to simple descriptors, a subjectheading list can include pre-coordinated strings composed of subject terms with subdivisions.The Library of Congress Subject Headings, which in print now comprises five large volumes, isprimarily a list of headings that have been used in the Library. Likewise Medical Subject Headingsderives from the holdings of the National Library of Medicine. The Sears List is unique amongsubject heading lists in that it does not attempt to be a complete list of terms used in any singlelibrary but only a list of headings most likely to be needed in a typical small library and a skeletonor pattern for creating other headings as needed. By using the Sears List as a foundation, thecataloger in a small library can develop a local authority list that is consistent in form andcomprehensive for that library. This has proven over the years to be a practical and economicalsolution to the cataloging needs of small libraries. In other ways, such as the use of uninvertedheadings only and of popular rather than technical vocabulary, the Sears List is specifically tailoredto the needs of small libraries of any kind, including school libraries, small public libraries, churchlibraries, etc.Because the Sears List is not a complete authority list, the cataloger using the Sears List must takean active part in developing a larger vocabulary of terms. As an aid in this process we offer thefollowing discussion of the basic principles of subject analysis and the construction and control ofsubject headings.A-18'