Library Classification Systems

01:00 Sun 24th Mar 2002 The AnswerBank

Q. Sounds gripping. Just how do librarians keep those books in order

A. Of course it's gripping. To try to categorise the sum of all human knowledge is, to say the least, a daunting - and fascinating - task. Librarians, as the keepers of such knowledge, at least as it appears in book form, use a variety of classification systems in order to organise their holdings. Some systems are more useful for public access, others for private access, and different systems have been devised in different countries, which may be geared specifically to given language or culture or specific to a particular academic discipline.

Q. Any examples

A. The Dutch devised a system called Nederlandse Basisclassificatie which is used in Holland and by some German libraries and the Swedes use a system called SAB.

Examples of subject-specific schemes are Engineering Information for - yes, you've guessed it - engineering, the National Library of Medicine Classification for medicine and the British Catalogue of Music Classification.

Q. What's the most popular system

A. In the English-speaking world it's the Dewey Decimal System of Classification. Devised in 1873 by Melvil Dewey (1851-1931) - the librarian of Amherst College Library, New York State - the system was quickly adopted in the USA and throughout the British Empire. It's what is known as a universal system, that is one which is not specific to any one field but which can be used in a multi-disciplinary way. These systems are far and away the most common means of classification, and others include the Universal Decimal Classification and the classification scheme devised by the Library of Congress in Washington, DC.

Q. And how does Dewey Decimal work

A. The system divides all knowledge up into 10 main classes, all of which are then subdivided. These classes are named and numbered as follows: 000-099, general works; 100-199, philosophy and psychology; 200-299, religion; 300-399, social sciences; 400-499, language; 500-599, natural sciences and mathematics; 600-699, technology; 700-799, the arts; 800-899, literature and rhetoric; and 900-999, history, biography and geography.

To illustrate how the subclasses work, here are some examples from natural sciences (500): 510, mathematics; 520 astronomy and allied sciences; 530 physics; 550 earth sciences; 560 palaeontology and palaeozoology; 570 life sciences; 580 botanical sciences; and 590 zoological sciences.

Smaller sub-sub-classes are then made. So, for example, within astronomy and allied sciences (520), you have: 523 specific celestial bodies & phenomena; 523.1 the universe; 523.2 the solar system; 523.3 the moon; 23.4 planets; 523.41 Mercury; 523.42 Venus; 523.3 get the idea.

Q. Do all systems operate in similar ways

A. In 1933 a major departure was made by the celebrated - don't mock, this is deep stuff - Indian library scientist called, Shiyali Ramamrita Ranganathan (1892-1972). Ranganathan devised what is known as the Colon System, which allows for greater flexibility in its sub-divisions, particularly for academic libraries.

Q. How does it work

A. It is general rather than specific in nature, and it can create complex or new categories through the use of facets, divided by colons. The system makes use of 108 main categories with 10 minor classes. An example of how it works can be seen in the way the category of dental surgery (L 214:4:7) is made up. This is done by combining the letter L for medicine, the number 214 for teeth, the number 4 for diseases and the number 7 for surgery. Simple.

Q. And what about the Internet

A. Well, it's all a bit of a mess at the moment. The billions of pages found on the Internet need to be organised so they can be browsed effectively. It has, of course, grown exponentially over the past ten years and along the way various systems have been put in place to try to sort out all the information produced. For example Yahoo!, since it started operation in 1994, has listed sites using their own universal classification scheme or 'ontology'. Each site collected for Yahoo! is listed under one of 20,000 categories or sub-categories.

Dublin Core Metadata has been devised to allow people to describe their own pages to the outside world and XML is used to organise the information within these pages, again making the information more accessible to the surfer. Neither, especially Dublin Core, have been taken up fully by page makers, but it's getting there.

See also the answerbank articles on Carnegie Libraries and ISBNs

For more on Arts & Literature click here

By Simon Smith

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