General overview and LCSH
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LCSH should be the first and main source for subject headings and if terms are offensive, outdated, inaccurate, or not specific enough other established alternative thesauri should be used in their place or to supplement them. Only alternative vocabularies with source codes assigned by the Library of Congress should be used. Generally, these vocabularies are specialized to describe a specific subject area and are not comprehensive and also do not have facets so are limited in their use for descriptive cataloging and should generally be seen as supplementary to LCSH when faceted headings are needed/desired. The use of locally created subject headings is NOT recommended. The purpose of controlled vocabularies and established thesauri are so that there is uniformity among description across libraries, this is especially important for libraries who use and contribute to shared catalogs, such as OCLC WorldCat. This allows for collocation of like materials when searching, since materials about the same subjects are described using the same language. It also allows for several authority control processes that maintain headings by updated/flipping terms when changes occur to the term's authority file. When a term is updated or changed with the LCSH, since the terms are all coded and should be controlled in OCLC Connexion, they are able to run processes to updated update all the terms in the records in most cases (split headings are an exception). There are also processes that run in local catalogs to update the terms once they have been changed in LCSH.
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Within Harvard Library the SACO Diversity, Inclusion, Belonging, and Anti-Racism Task Group (SACO DIBAR Task Group) "is charged with reviewing controlled terms governed by the Library of Congress Subject Authority Cooperative Program (SACO) for possible revision in light of EDIBA principles." Their wiki page tracks headings under consideration and includes a form for staff to submit terms for the group to review, they ask for the following information with each submission: the existing term, a proposed preferred term, the MMS ID of the corresponding bibliographic record in Alma, and references to any related sources and/or justification/reasoning for the change.
There are also some long standing groups working with the Library of Congress Program for Cooperative Cataloging (PCC) to make the LCSH more inclusive and comprehensive in areas that need more terms for fuller access.
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