Universal Decimal Classification structure and use


UDC is structured according to traditional disciplines of study, but is highly flexible to allow for constant revision in order to keep pace with development of knowledge. The UDC Master Reference File (MRF) is updated yearly.

UDC’s most innovative and influential feature is its ability to express not just simple subjects but relations between subjects. This facility is added to a hierarchic structure, in which knowledge is divided into ten classes, then each class is subdivided into its logical parts, each subdivision is further subdivided, and so on.

UDC Hierarchy

The ten top-level tables are:

     0. Generalities
     1. Philosophy. Psychology
     2. Religion. Theology
     3. Social sciences
     4. (Under development)
     5. Mathematics and natural sciences
     6. Applied sciences. Medicine. Technology
     7. The arts. Recreation. Entertainment. Sport
     8. Language. Linguistics. Literature
     9. Geography. Biography. History


How to use

Originally intended for organizing documentation on everything that had ever been written, UDC has exceeded its parent, the Dewey Decimal Classification, both in the size of its vocabulary and its indexing capabilities.

Its main strength however is that it preserves a logical structure and works equally well whether it is used only at an abridged level or applied to itsfull extent.

UDC can be used for organizing and recording different kinds of objects, files, books or information resources. The scheme has been used to classify motion pictures by subject, map collections by place, and to catalogue collections of stamps, coins and metal soldiers.

In fact, UDC can be used to index anything to exploit a field of interest to the full, and to enable efficient retrieval of information. UDC is now being used to arrange directories on the internet. Its application spreads almost universally across.



- shelf arrangement
- information retrieval (classified catalogues)
- collection management (acquisition, circulation statistics, weeding)
Museums and archives
- collection management
- objects indexing and retrieval
- collection display
Bibliographies and bibliographic databases
- subject information navigation
- information retrieval
Information services
- selective dissemination of information (user’s profile description)
- subject gateways (information presentation and navigation)
- metadata (information discovery).

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