This statement attempts to describe both the principles that underlie the structure of the Library of Congress subject headings system and the policies that govern the assignment of subject headings to LC MARC records. Principles of construction and policies of application are treated separately because the same subject headings list may be used by different agencies according to different policies with significantly different results.

In intent, the statement sets forth the assumptions and practices that are currently operative at the Library of Congress. It is not a statement of an ideal subject headings list or thesaurus. It is prepared on the premise that improvement in any system must rest on a thorough understanding of its current state.

Furthermore, the statement is not a full code; detailed guidelines and instructions already exist in the Subject Cataloging Manual. Nor is it an explanation of all the headings in Library of Congress Subject Headings, which, as a cumulative list begun almost a century ago, contains headings that reflect philosophies and policies followed over many years. In sum, the statement presents, first, the underlying principles that govern current work on the formulation of LC subject headings and on the structure of the subject headings list as a whole, and, second, the general policies that govern the assignment of subject headings to MARC records.

See also:

Introduction to LCSH