A preferred, authorized heading used in a vocabulary, particularly a bibliographic authority file, typically including a string of names or terms with additional information as necessary to allow disambiguation between identical headings (for example, United States——History——Civil War, 1861-1865——Battlefields and United States——History——Civil War, 1861-1865——Campaigns). The types of authority headings used by the U.S. Library of Congress are subject authority headings, name authority headings, title authority headings, name/title authority headings, and keyword authority headings.