Subject heading lists and their features.

The Subject Heading Lists are standardized, controlled vocabularies that serve as crucial tools in Subject Cataloguing, providing specific verbal access points to library materials. They are designed to bring uniformity and standardization to the subject headings used in catalogues.

The sources highlight two major standard subject heading lists used for determining subject headings in the English language: the Sears List of Subject Headings (SLSH) and the Library of Congress Subject Headings (LCSH).

I. General Features and Utility of Subject Heading Lists

A subject heading list is a master list of terms (preferred terms) that can be assigned to documents.

A. Purpose and Function

1. Vocabulary Control: The primary function is to control the terminology used in subject catalogues and indexes.
2. Standardization and Uniformity: These lists ensure the uniformity and standardization in the subject headings derived by cataloguers.
3. Guidance and Experience: They act as a dictionary or collection of subject headings and provide guidelines to the cataloguer, offering the benefit of the experience of many other cataloguers.
4. User-Centric Terminology: The pre-prepared subject headings in these lists are ideally formulated according to the needs of the users.
5. Cross-References: They indicate the use of cross-references to guide the users to related terms and synonyms.

B. Limitations

1. Incompleteness: Subject heading lists are never complete and up-to-date because new subjects are introduced constantly, necessitating continuous inclusion of these subjects.
2. Resource Intensive: Collection and printing require enough time and effort, and separate lists must be prepared for each language.
3. Lack of Suitability for Specialization: General subject heading lists are not useful for specialized libraries.
4. Bias: Historically, such lists are heavily biased towards the country and culture of their origin, requiring indexers in other countries to make many adaptations and additions.

II. Library of Congress Subject Headings (LCSH)

The Library of Congress Subject Headings (LCSH) is arguably the most widely adopted subject indexing language in the world and is intended for larger libraries with fairly comprehensive collections.

A. Development and Scope

• Origin: LCSH has been actively maintained by the United States Library of Congress since 1898 to catalogue materials held at the Library of Congress.
• Format: It comprises a thesaurus (in the information technology sense) of subject headings.
• Detail and Complexity: The LCSH list is much more detailed and tends to use more complex terminology in describing subjects compared to SLSH. It currently occupies five very large volumes.
• Uniform Access: The widespread use of LCSH facilitates the uniform access and retrieval of items in any library in the world using the same search strategy and thesaurus.
• Updating: The Library of Congress issues weekly updates. Its monthly and cumulated lists of changes and revisions represent a highly-developed technique for acquainting using libraries promptly with modifications.

B. Usage and Application

• Access Tool: LCSH are applied to every item within a library's collection and facilitate a user's access to items that pertain to similar subject matter, reducing the enormous time needed to search only by author or title.
• Data Access: LCSH is published in large red volumes. The data is also available via subscription services like the Library of Congress Classification Web, or free of charge (as individual records) at Library of Congress Authorities.
• OPAC Integration: LCSH is an excellent resource for finding relevant material in a library catalogue. Web-based Online Public Access Catalogues (OPACs) often allow users to hyperlink to a list of similar items displayed by LCSH once one item of interest is located.
• Indexing: In MARC records, DDC numbers are often linked to LCSH headings by most major bibliographic services. The USMARC format contains tags for subject headings including LCSH and MeSH.

III. Sears List of Subject Headings (SLSH)

The Sears List of Subject Headings (SLSH) was designed to meet the requirements of small and medium-sized libraries that needed broader subject headings.

A. Development and Scope

• Origin: SLSH was first designed in 1923 by Minnie Earl Sears to fulfill the demands of small American libraries that found LCSH too big and specialized.
• Scope Expansion: It has enlarged its scope to meet the requirements of medium-sized libraries.
• Objective: The objective of SLSH is to keep the documents of a specific subject under a uniform subject heading.
• Terminology: SLSH uses less specific terminology and fewer subdivisions than LCSH.
• Thesaurus Format: Since its 15th edition, SLSH has adopted a thesaurus format using standard abbreviations like NT (Narrower Term), BT (Broader Term), RT (Related Term), USE, and SA (See Also), conforming to ANSI/NISO standards.
• Guidance Provision: SLSH provides provision for the specific entry principle, the sub-division of subjects, the use of geographical names, plural forms, and the use of normally popular words.

B. Cross-References in SLSH

SLSH is structured to aid the cataloguer in determining cross-references. Headings are given with notations like 'x', 'xx', and 'see also' to guide the formation of 'see' and 'see also' directions.

• 'See also' headings (XX or BT/NT/RT): These can be used for selecting appropriate headings for related documents to be catalogued.
• 'X' headings (USE): If a 'see also' item is selected for the subject heading, then 'see' directions will be given from the headings listed after 'X'.