Universal Decimal Classification

Universal Decimal Classification
M0tty · CC BY-SA 4.0 · source
Name	Universal Decimal Classification
Classification	Dewey-based, faceted
Released	0 1899
Creator	Paul Otlet, Henri La Fontaine
Latest version	UDC Summary, 2022
Company	UDC Consortium
Website	https://www.udcsummary.info

Universal Decimal Classification. The Universal Decimal Classification is a sophisticated, multilingual bibliographic and library classification system. It was developed from the Dewey Decimal Classification by the Belgian bibliographers Paul Otlet and Henri La Fontaine at the turn of the 20th century. As a highly faceted scheme, it allows for the precise and complex classification of all fields of knowledge, widely used in bibliographic databases, research libraries, and documentation centers internationally.

Overview and history

The system was conceived in 1895 by Paul Otlet and Henri La Fontaine, founders of the Institut International de Bibliographie in Brussels. Their ambitious project, the Universal Bibliographic Repertory, required a detailed indexing system, leading them to adapt Melvil Dewey's scheme. The first full edition was published in French between 1904 and 1907. Following the dissolution of the Institut International de Bibliographie, stewardship passed to the Fédération Internationale de Documentation and later to the UDC Consortium, based in The Hague. The classification's development has been closely associated with major documentation movements, including the World Congress of Universal Documentation held in Paris.

Structure and notation

The structure uses Arabic numerals in a decimal fraction notation, inherited from the Dewey Decimal Classification. Its core innovation is the introduction of facet indicators, or auxiliary signs, which allow for synthesis and complex number building. Key symbols include the plus sign for addition, the slash for extension, and relation signs like the colon to link distinct subjects. The system also employs brackets, apostrophes, and equals signs to denote various relationships, geographical subdivisions, and time periods. This notation enables the creation of highly specific class numbers far beyond a simple enumerative list.

Main tables and classes

The main tables organize knowledge into ten primary classes, from 0 for generalities to 9 for geography, biography, and history. Key divisions include class 1 for philosophy and psychology, class 2 for religion and theology, and class 3 for the social sciences. Class 5 covers mathematics and natural sciences, while class 6 is devoted to applied sciences, medicine, and technology. Classes 7 and 8 cover the arts, recreation, and literature, respectively. Each main class is further subdivided hierarchically; for instance, 54 under class 5 pertains to chemistry, and 621.3 under class 6 relates to electrical engineering.

Use and application

It is employed globally in over 130 countries for organizing library collections, national bibliographies, and institutional repositories. Major implementations include its use in the British National Bibliography for many years and in numerous United Nations agency libraries. The system is particularly valued in scientific and technical libraries, such as those serving the European Organization for Nuclear Research and various institutes within the Russian Academy of Sciences. Its ability to create precise, compound numbers makes it ideal for indexing articles in specialized databases and organizing archives in documentation centers.

Comparison with other classification systems

Unlike the purely hierarchical Dewey Decimal Classification or the Library of Congress Classification, it is a fully faceted classification system from its inception. While the Bliss bibliographic classification also employs facets, it is less widely adopted internationally. The Colon classification developed by S. R. Ranganathan shares a philosophical emphasis on facet analysis but uses a very different notation. Compared to the broad categories of the Library of Congress Classification, it offers more detailed and synthetic notation for scientific and technical subjects, though it is less commonly used in large general research libraries in North America.

Development and maintenance

Ongoing development is managed by the UDC Consortium, which comprises publisher Brill and the International Federation of Library Associations and Institutions. Revisions and updates are proposed by an international network of editors and subject experts, with major new editions published in the Master Reference File. The scheme is translated into over 40 languages, including versions in Chinese, Japanese, and Russian. Regular updates reflect advances in fields like information technology and bioethics, ensuring its continued relevance for modern knowledge organization in institutions like the National Library of Serbia.

Category:Library classification systems