The Library of Congress collections serve as the literary warrant (i.e., the literature on which the controlled vocabulary is based) for the Library of Congress subject headings system. The number and specificity of subject headings included in the Subject Authority File (the machine-readable database containing the master file of Library of Congress subject headings from which the printed list, the microform list, the CDMARC SUBJECTS, etc. are generated), are determined by the nature and scope of the Library of Congress collections. Subject headings are established as they are needed to catalog the materials being added to the collection or to establish links among existing headings. In recent years, headings contributed by libraries engaged in cooperative activities with the Library of Congress based on the needs of their collections have also been included.

3.2 References

See also:

3.0 Fundamental principles of Library of Congress Subject Headings