Library classification

A library classification is a system of coding and organizing library materials (books, serials, audiovisual materials, computer files, maps, manuscripts, realia) according to their subject. A classification consists of tables of subject headings and classification schedules used to assign a class number to each item being classified, based on that item's subject.

Until the 19th century, most libraries had closed stacks, so the library classification only served to organize the subject catalog. In the 20th century, libraries opened their stacks to the public and started to shelve the library material itself according to some library classification to simplify subject browsing.

Types

There are many standard systems of library classification in use, and many more have been proposed over the years. These include:

Used in English-speaking world

• Bliss bibliographic classification (BC)
• Dewey Decimal Classification (DDC)
• Library of Congress Classification (LC)
• Dickinson classification

(These are the most common in the English-speaking world.)

Collections in other languages

• Nippon Decimal Classification (NDC)
• Principes de classement des documents musicaux (PCDM)
• Chinese Library Classification (CLC)
• Korean Decimal Classification (KDC)

Based upon synthesis

• Bliss bibliographic classification
• Colon classification
• Cutter Expansive Classification
• Universal Decimal Classification
• Brinkler classification

(These systems are often considered to be theoretically superior, since they make use of the principle of synthesis (combining codes from different lists to represent the different attributes of a work), which is comparatively lacking in LC or DDC.)

Classification

There are three main types of classification systems:

• enumerative: produce an alphabetical list of subject headings, assign numbers to each heading in alphabetical order
• hierarchical: divides subjects hierarchically, from most general to most specific
• faceted or analytico-synthetic: divides subjects into mutually exclusive orthogonal facets

The most common classification systems, LC and DDC, are essentially enumerative, though with some hierarchical and faceted elements, especially at the broadest and most general level. The first true faceted system was the Colon classification of S. R. Ranganathan.

Specialist classification systems have been developed for particular subject areas, and some specialist libraries develop their own classification system that emphasises those areas they specialise in.An example specialist classification system for art and iconography is Iconclass. Another example are the Medical Subject Headings devised by the US National Library of Medicine (NLM). There are also emerging metadata standards that are being developed for web resources, digital images, and other specialized materials.

Library classification forms part of the field of library and information science. It goes hand in hand with library (descriptive) cataloging under the rubric of cataloging and classification. The library professional who engages in the process of cataloging and classifying library materials is called a cataloger or catalog librarian.

See also

• Categorization

External links

• An annotated bibliography on Library Classification and Subject Approaches to Information - by Salman Haider, Librarian (Cataloging), US Library of Congress, New Delhi Overseas Office

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