General Classification Schemes / Universal Classification Schemes

General or universal systems of knowledge organization are opposed to special knowledge organizing systems. While the Dewey Decimal Classification is a universal system, the classification used in PsycINFO is a special scheme. Some “general schemes” tend to be a series of special schemes (e.g. Bliss 2nd edition and Library of Congress Classification, LCC).


General systems are mostly used in public libraries and in collections covering all subjects, while special schemes are mostly used in special libraries and subject bibliographies.


While a special scheme may reflect the point of view of a specific domain or approach, a general scheme must always be a compromise between different disciplinary and theoretical points of view. An example from the Danish Dewey System, DK5, about anthropology by Jan Ovesen is translated and cited in Hjørland (2002, p. 427). As stated in, for example, Mai (2004) and Vickery (1960, p. 7), general systems have often been regarded as unsatisfactory from the point of view of a specific subject.


In both universal and special schemes it is important how specific fields are represented. Both kinds of systems thus demands subject expertise for their construction, administration and evaluation. In this respect is a general classification system to be regarded as a synthesis of special schemes.


Sometimes a somewhat mystical understanding of general classification systems covering "the universe of knowledge" is expressed. Two things are important to consider:


1) it is not difficult to make a classification which cover all possible subjects, past, present and future. This might be done, for example, by dividing subjects to those concerning with living creatures and all other subjects, or, as in the game "20 questions to the professor" to have a broad systems of categories like animal kingdom, plant kingdom, mineral kingdom and abstract concepts (as long as a class for "other subjects" is maintained). 


2) Real life classifications are based on their warrants (literary or other kind). This is simply their empirical basis. If a system is based on monographs, is less suited for articles, not to mention archival records or physical objects. No system is thus "universal", although it may, as Library of Congress Classification, be based on very comprehensive collections. But a system will always be biased by the warrant on which it is based.


It follows that special knowledge organizing systems, such as the system developed for Chemical Abstracts, can be made much more specific compared to general systems that are based on broader collections.





Hjørland, B. (2002). Domain analysis in information science. Eleven approaches - traditional as well as innovative. Journal of Documentation, 58(4), 422-462.




Mai, J.-E. (2004).The Future of General Classification. Cataloging and Classification Quarterly, 37 (1/2): 3-12.

(Visited March 16, 2004).


Vickery, B. C. (1960). Faceted Classification: A Guide to Construction and Use of Special Schemes. London: Aslib.


See also: Special KOS

Universal classification systems


Birger Hjørland

Last edited: 24-01-2007