In addition to routine maintenance of headings to reflect vocabulary changes, changes of policies governing the formulation of headings, and changes in the MARC tagging practices, there are two other situations where headings are modified.

One is an obvious change in the scope of a serial’s coverage that is not at the same time signaled by a change in title.  A title that expands its coverage beyond the United States to include Canada would require additional, parallel subject headings for Canada.  A title that broadens from national to international scope should have the geographic subdivisions deleted from the subject headings.

Another instance is the establishment of a new vocabulary term offering a degree of specificity not previously available, which more closely matches the subject matter of a serial title than does the existing heading(s).  For some vocabulary systems, newly-established terms are not merely applied prospectively; for example, new LCSH terms are assigned to previously-cataloged records whenever it is determined that they are needed to replace existing headings that are overly broad.

For example, when the LCSH heading Multiple criteria decision making was established, serials such as

MCDM worldScan :  $b the thrice yearly newsletter of the International Special Interest Group on Multiple Criteria Decision Making

650  #0  $a Decision making $v Periodicals.

Changed to:

650  #0  $a Multiple criteria decision making $v Periodicals.

Changes to other subject-related elements, such as fields 043 and 008/24-27, are made at the same time.

See also:

Module 15.  Subject Headings