A word or phrase which describes the overall subject content of a book or other work using the wording devised by the Library of Congress. Commonly called "LCSH." The Subject Search option in the UNL University Libraries' catalog uses LCSH, including cross-references from similar terms. The Keyword Search option searches the words in the subject headings in the catalog record, along with other elements, but does not use the cross-references. NOTE: subject headings are not assigned to UNL theses and dissertations unless the subject matter deals with Nebraska.