Library of Congress Subject Headings
Encyclopedia
The Library of Congress Subject Headings (LCSH) comprise a thesaurus
(in the information technology
sense, a controlled vocabulary
) of subject headings, maintained by the United States Library of Congress
, for use in bibliographic records. LC Subject Headings are an integral part of bibliographic control
, which is the function by which libraries collect, organize and disseminate documents. LCSHs are applied to every item within a library’s collection, and facilitate a user’s access to items in the catalogue that pertain to similar subject matter. If users could only locate items by ‘title’ or other descriptive fields, such as ‘author’ or ‘publisher’, they would have to expend an enormous amount of time searching for items of related subject matter, and undoubtedly miss locating many items because of the ineffective and inefficient search capability.
, if the correct headings have been applied to the item by the library. Thus, LCSH decisions involve a great amount of debate and even controversy in the library community.
Despite LCSH's wide-ranging and comprehensive scope, there are libraries where the use of LCSH is not ideal or effective. To deal with these types of collections and user communities, other subject headings may be required. The United States National Library of Medicine developed Medical Subject Headings
(MeSH
) to use on its many health science databases and collection. Many university libraries may not apply both LCSH and MeSH headings to items. In Canada, the National Library of Canada worked with LCSH representatives to create a complementary set of Canadian Subject Headings
(CSH) to access and express the topic content of documents on Canada
and Canadian topics.
faculties about the cultural and gender biases that affect the terms used in LCSH, which in turn may limit or deprive library users access to information stored and disseminated in collections. A notable American Library Science scholar on this subject is Sanford Berman
.
A web service, lcsh.info, was set up by Ed Summers, a Library of Congress employee, circa April 2008, using SKOS
to allow for simple browsing of the subject headings. lcsh.info was shut down by the Library of Congress's order on December 18, 2008. This announcement was met with great dismay from the library science and semantic web communities, e.g. Tim Berners-Lee
and Tim Spalding of LibraryThing
. After some delay, the Library did set up its own web service for LCSH browsing at id.loc.gov in April 2009.
ed, web-based Online Public Access Catalogues, or OPAC
s, allow users to hyperlink to a list of similar items displayed by LCSH once one item of interest is located. However, because LCSH are not necessarily expressed in natural language, many users may choose to search OPACs by keywords. Moreover, users unfamiliar with OPAC searching and LCSH, may incorrectly assume their library has no items on their desired topic, if they chose to search by ‘subject’ field, and the terms they entered do not strictly conform to a LCSH. For example ‘body temperature regulation’ is used in place of ‘thermoregulation’. Thus the easiest way to find and use LCSH is to start with a ‘keyword’ search and then look at the Subject Headings of a relevant item to locate other related material.
Thesaurus
A thesaurus is a reference work that lists words grouped together according to similarity of meaning , in contrast to a dictionary, which contains definitions and pronunciations...
(in the information technology
Information technology
Information technology is the acquisition, processing, storage and dissemination of vocal, pictorial, textual and numerical information by a microelectronics-based combination of computing and telecommunications...
sense, a controlled vocabulary
Controlled vocabulary
Controlled vocabularies provide a way to organize knowledge for subsequent retrieval. They are used in subject indexing schemes, subject headings, thesauri, taxonomies and other form of knowledge organization systems...
) of subject headings, maintained by the United States Library of Congress
Library of Congress
The Library of Congress is the research library of the United States Congress, de facto national library of the United States, and the oldest federal cultural institution in the United States. Located in three buildings in Washington, D.C., it is the largest library in the world by shelf space and...
, for use in bibliographic records. LC Subject Headings are an integral part of bibliographic control
Bibliographic control
In library and information science, bibliographic control is the process by which information resources are described so that users are able to find and select that information resource. An information resource could be a book, a movie, or an image, among other things...
, which is the function by which libraries collect, organize and disseminate documents. LCSHs are applied to every item within a library’s collection, and facilitate a user’s access to items in the catalogue that pertain to similar subject matter. If users could only locate items by ‘title’ or other descriptive fields, such as ‘author’ or ‘publisher’, they would have to expend an enormous amount of time searching for items of related subject matter, and undoubtedly miss locating many items because of the ineffective and inefficient search capability.
An art and a science
Subject heading classification is a human and intellectual endeavor, where trained professionals apply topic descriptions to items in their collections. Naturally, every library may choose to categorize the subject matter of their items differently, without a uniform consentaneous standard. The widespread use and acceptance of the Library of Congress Subject Headings facilitates the uniform access and retrieval of items in any library in the world using the same search strategy and LCSH thesaurusThesaurus
A thesaurus is a reference work that lists words grouped together according to similarity of meaning , in contrast to a dictionary, which contains definitions and pronunciations...
, if the correct headings have been applied to the item by the library. Thus, LCSH decisions involve a great amount of debate and even controversy in the library community.
Despite LCSH's wide-ranging and comprehensive scope, there are libraries where the use of LCSH is not ideal or effective. To deal with these types of collections and user communities, other subject headings may be required. The United States National Library of Medicine developed Medical Subject Headings
Medical Subject Headings
Medical Subject Headings is a comprehensive controlled vocabulary for the purpose of indexing journal articles and books in the life sciences; it can also serve as a thesaurus that facilitates searching...
(MeSH
Medical Subject Headings
Medical Subject Headings is a comprehensive controlled vocabulary for the purpose of indexing journal articles and books in the life sciences; it can also serve as a thesaurus that facilitates searching...
) to use on its many health science databases and collection. Many university libraries may not apply both LCSH and MeSH headings to items. In Canada, the National Library of Canada worked with LCSH representatives to create a complementary set of Canadian Subject Headings
Canadian Subject Headings
Canadian Subject Headings is a list of subject headings in the English language, using controlled vocabulary, to access and express the topic content of documents on Canada and Canadian topics. Library and Archives Canada publishes and maintains CSH on the Web...
(CSH) to access and express the topic content of documents on Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
and Canadian topics.
LCSH policy issues
Historically, issues have revolved around the terms employed to describe racial or ethnic groups. Notable has been the terms used to describe African-Americans. Until the 1990s, the LCSH administrators had a strict policy of not changing terms for a subject category. This was enforced to tighten and eliminate the duplication or confusion that might arise if subject headings were changed. Therefore, one term to describe African-American topics in LCSH was ‘Afro-American’ long after that term lost currency and acceptance in the population. LCSH decided to allow some alteration of terms in 1996 to better reflect the needs and access of library users. Nevertheless, many common terms, or ‘natural language’ terms are not used in LCSH, and may in effect limit the ability for users to locate items. There is a growing tradition of research in Library and Information ScienceLibrary and information science
Library and information science is a merging of the two fields library science and information science...
faculties about the cultural and gender biases that affect the terms used in LCSH, which in turn may limit or deprive library users access to information stored and disseminated in collections. A notable American Library Science scholar on this subject is Sanford Berman
Sanford Berman
Sanford Berman is a radical librarian known for promoting alternative viewpoints in librarianship and acting as a pro-active information conduit to other librarians around the world, mostly via public speaking, voluminous correspondence, and unsolicited "care packages" delivered via the U.S....
.
Data access
The Subject Headings are published in large red volumes (currently five), which are typically displayed in the reference sections of research libraries. They may also be searched online in the Library of Congress Classification Web, a subscription service, or free of charge (as individual records) at Library of Congress Authorities. The Library of Congress issues weekly updates. The data is published for a fee by the Cataloging Distribution Service.A web service, lcsh.info, was set up by Ed Summers, a Library of Congress employee, circa April 2008, using SKOS
SKOS
Simple Knowledge Organization System is a family of formal languages designed for representation of thesauri, classification schemes, taxonomies, subject-heading systems, or any other type of structured controlled vocabulary. SKOS is built upon RDF and RDFS, and its main objective is to enable...
to allow for simple browsing of the subject headings. lcsh.info was shut down by the Library of Congress's order on December 18, 2008. This announcement was met with great dismay from the library science and semantic web communities, e.g. Tim Berners-Lee
Tim Berners-Lee
Sir Timothy John "Tim" Berners-Lee, , also known as "TimBL", is a British computer scientist, MIT professor and the inventor of the World Wide Web...
and Tim Spalding of LibraryThing
LibraryThing
LibraryThing is a social cataloging web application for storing and sharing book catalogs and various types of book metadata. It is used by individuals, authors, libraries and publishers....
. After some delay, the Library did set up its own web service for LCSH browsing at id.loc.gov in April 2009.
Using LCSH
Once a library user has found the right subject heading(s), they are an excellent resource for finding relevant material in the library catalogue. Increasingly the use of hyperlinkHyperlink
In computing, a hyperlink is a reference to data that the reader can directly follow, or that is followed automatically. A hyperlink points to a whole document or to a specific element within a document. Hypertext is text with hyperlinks...
ed, web-based Online Public Access Catalogues, or OPAC
OPAC
An Online Public Access Catalog is an online database of materials held by a library or group of libraries...
s, allow users to hyperlink to a list of similar items displayed by LCSH once one item of interest is located. However, because LCSH are not necessarily expressed in natural language, many users may choose to search OPACs by keywords. Moreover, users unfamiliar with OPAC searching and LCSH, may incorrectly assume their library has no items on their desired topic, if they chose to search by ‘subject’ field, and the terms they entered do not strictly conform to a LCSH. For example ‘body temperature regulation’ is used in place of ‘thermoregulation’. Thus the easiest way to find and use LCSH is to start with a ‘keyword’ search and then look at the Subject Headings of a relevant item to locate other related material.
See also
- Library of Congress ClassificationLibrary of Congress ClassificationThe Library of Congress Classification is a system of library classification developed by the Library of Congress. It is used by most research and academic libraries in the U.S. and several other countries; for example, Australia and Taiwan, R.O.C. It is not to be confused with the Library of...
- Minnie Earl SearsMinnie Earl SearsMinnie Earl Sears formulated the Sears Subject Headings, a simplification of the Library of Congress Subject Headings.-Life and work:...
: formulated the Sears Subject Headings, a simplification for use by small libraries.
External links
- Browse LCSH online
- Library of Congress Cataloging home page
- Cataloging Distribution Service – primary source of Library of Congress Subject Headings
- Library of Congress Authorities – allows users to look through the subject headings at no charge