Subject Heading Systems

Subject heading systems are standardized vocabularies used by libraries, archives, and information systems to categorize and classify materials by subject. These systems are essential for organizing resources, making it easier for users to search, discover, and access relevant information. Various subject heading systems exist, each designed with particular features and purposes, ranging from highly detailed and hierarchical systems to more flexible, simplified ones. Below is an overview of some of the most widely used subject heading systems:

1. Library of Congress Subject Headings (LCSH)

• Overview: LCSH is one of the most comprehensive and widely used subject heading systems. It is maintained by the Library of Congress and provides a controlled vocabulary for classifying books, articles, and other library resources.
  
  

• Key Features:
  
  

  • Hierarchical Structure: LCSH uses broader and narrower terms, allowing for a hierarchical organization of subjects.
    
    

  • Cross-references: LCSH includes see and see also references to guide users to related or alternative terms.
    
    

  • Specificity: It offers highly detailed terms, often covering specific subtopics, disciplines, and interdisciplinary subjects.
    
    

• Use Case: Used by most large academic libraries and research institutions, LCSH is ideal for extensive collections requiring detailed classification.
  
  

• Example:
  
  

  • Main heading: "Artificial Intelligence"
    
    

    • Broader term: "Computer Science"
      
      

    • Narrower term: "Machine Learning"
      
      

    • Related term: "Cognitive Science"
      
      

    • See also: "Expert Systems"
      
      

2. Sears List of Subject Headings

• Overview: The Sears List of Subject Headings is a simplified subject heading system often used in smaller or public libraries. It was developed to be more accessible than LCSH, while still providing a controlled vocabulary for classification.
  
  

• Key Features:
  
  

  • Simplicity: Sears offers shorter, simpler headings that are easier to understand and apply than LCSH.
    
    

  • More Generalized: It focuses on more general subjects, making it better suited for smaller collections that do not require the level of detail found in LCSH.
    
    

  • Fewer Hierarchical Layers: Sears does not use as many hierarchical relationships as LCSH.
    
    

• Use Case: Ideal for small libraries or schools that need a straightforward, easy-to-use classification system for their resources.
  
  

• Example:
  
  

  • Subject heading: "Computers"
    
    

  • Broader term: "Technology"
    
    

  • See also: "Data Processing"
    
    

3. Faceted Application of Subject Terminology (FAST)

• Overview: FAST is a subject heading system developed by the OCLC (Online Computer Library Center). It is based on the Library of Congress Subject Headings (LCSH) but simplifies the structure by organizing terms into facets, each representing different aspects of a subject.
  
  

• Key Features:
  
  

  • Faceted Classification: FAST organizes subjects into multiple facets such as topic, geographic region, time period, and form. This allows for multi-dimensional classification of a topic.
    
    

  • Simplified Structure: It removes complex hierarchical relationships and makes subject classification easier to apply.
    
    

  • Interdisciplinary: FAST is ideal for categorizing interdisciplinary subjects where topics span multiple areas (e.g., a book about climate change could be classified under topics like science, politics, and sociology).
    
    

• Use Case: FAST is used in digital libraries, online catalogs, and smaller library systems where simplicity and flexibility are key.
  
  

• Example:
  
  

  • Subject heading: "Digital Transformation"
    
    

    • Topical: "Technology"
      
      

    • Geographic: "Global"
      
      

    • Chronological: "21st Century"
      
      

    • Form: "Case Studies"
      
      

4. Polythematic Structured Subject Heading System (PSH)

• Overview: The Polythematic Structured Subject Heading System (PSH) is a subject heading system designed to classify topics that involve multiple themes or disciplines. It organizes subject terms so that they can reflect a variety of perspectives or aspects of a topic.
  
  

• Key Features:
  
  

  • Multiple Themes: PSH allows a single subject to encompass multiple thematic areas simultaneously (e.g., a single heading can reflect scientific, political, and social aspects of a topic).
    
    

  • Hierarchical Structure: PSH still includes hierarchical relationships (broader/narrower terms), but it is focused on ensuring that multi-dimensional topics are fully captured.
    
    

• Use Case: PSH is used in environments where topics are often interdisciplinary and require categorization across multiple thematic areas.
  
  

• Example:
  
  

  • Subject heading: "Social Media"
    
    

    • Topical: "Technology"
      
      

    • Sociological: "Cultural Impact"
      
      

    • Political: "Public Policy"
      
      

5. Subject Headings for School Libraries (SHSL)

• Overview: This system is designed specifically for school libraries, offering a more simplified and straightforward approach than systems like LCSH. It provides essential subject headings to help categorize books and materials that are typically found in school libraries.
  
  

• Key Features:
  
  

  • Ease of Use: SHSL is designed to be easy to implement by school librarians, teachers, and students.
    
    

  • Curriculum-focused: The headings are focused on subject areas relevant to school curricula.
    
    

  • Limited Scope: It doesn't offer the extensive range of terms found in larger systems like LCSH but provides a solid foundation for organizing basic resources.
    
    

• Use Case: Primarily used in K-12 schools and public libraries serving children.
  
  

• Example:
  
  

  • Subject heading: "History of the United States"
    
    

  • See also: "American Revolution"
    
    

6. Universal Decimal Classification (UDC)

• Overview: While not a subject heading system in the strict sense, the Universal Decimal Classification (UDC) is a numeric system used for classifying knowledge. It organizes subjects in a hierarchical way, using numbers and decimal points to represent different topics and subtopics.
  
  

• Key Features:
  
  

  • Numeric System: UDC uses a decimal system to represent subjects. The structure allows for detailed and granular classification.
    
    

  • International Use: UDC is used internationally, particularly in scientific and academic libraries.
    
    

• Use Case: UDC is typically used in larger academic and research libraries, especially those with extensive collections in science and technology.
  
  

• Example:
  
  

  • 004: Computer science
    
    

  • 004.6: Artificial intelligence
    
    

7. MESH (Medical Subject Headings)

• Overview: Developed by the National Library of Medicine (NLM), MeSH is a specialized controlled vocabulary for the classification of medical and health-related resources.
  
  

• Key Features:
  
  

  • Medical Focus: MeSH is specific to medical and biological topics, making it ideal for healthcare professionals, researchers, and medical libraries.
    
    

  • Hierarchical Structure: Like LCSH, MeSH is organized into broader and narrower terms, allowing for detailed classification of medical topics.
    
    

• Use Case: MeSH is used by medical libraries, research institutions, and health professionals for cataloging biomedical literature.
  
  

• Example:
  
  

  • Main heading: "Diabetes Mellitus"
    
    

    • Broader term: "Endocrine Diseases"
      
      

    • Narrower term: "Type 1 Diabetes"
      
      

    • Related term: "Insulin"
      
      

Conclusion

Subject heading systems play a critical role in organizing and classifying information, making it easier for users to search and access relevant resources. Whether using a detailed system like LCSH, a simplified one like Sears, or a flexible system like FAST, the goal is to ensure consistency and efficiency in categorizing materials. The choice of system depends on the size of the collection, the audience's needs, and the specific objectives of the cataloging process.