Facet, facet analysis and the facet-analytic paradigm

in knowledge organization (KO)
Etymologically “facet” means “little face” and is used in ordinary language about the cut sides of a diamond. The word has been used independently in psychology (cf., Krauth, 1981) and in Library and information Science (LIS). In LIS it is used both in electronic retrieval and in classification theory (and these two applications seem to have been isolated from each other in the literature).


S. R. Ranganathan was the first to introduce the word "facet" in Library and Information Science (LIS), and the first to consistently develop the theory of facet analysis. His Colon system was the first classification to apply the principles of facet analysis. The BC2 system is probably today the theoretically most advanced system based on this theory (and has also contributed to the further development of this approach). Faceted classification schemes consist of building blocks as opposed to enumerative systems. In this tradition Taylor (1992) defines facets as "clearly defined, mutually exclusive, and collectively exhaustive aspects, properties, or characteristics of a class or specific subject."

In the context of online searching Harter (1986, p. 172) writes: "A facet is a group of concepts that, for a given search, will be considered to be equivalent by the searcher [i.e. synonyms]. There may be several facets in a search, but usually there are no more than tree or four".

On p. 244 the concept is explained this way: "Facet-a concept group, consisting of terms that will be considered to be equivalent by a searcher for purposes of a given information need. Terms representing these concepts will be searched and the union of the resulting sets created using Boolean OR. See also hedge". [p. 245: "Hedge- a collection of terms for representing a facet in a given database. Hedges-are indented to be re-used for frequently needed facets, e.g. for the concept of "research""]. For a good introduction to the application of facets in search strategies see Harter’s chapter "Search Strategies and Heuristics" (1986, 170-204).

Faceted classification is also called analytic-synthetic, (sometimes just synthetic) named after the two main processes involved in the composition of a call number: Analysis, breaking down each subject into its basic concepts and synthesis, combining the relevant units and concepts to describe the subject matter of the document.

In classification theory Mills & Broughton (1977, p. 38) writes: "A facet may be defined as the total set of subclasses produced when a class is divided by a single broad principle....". At the same page are arrays defined as sub-facets: "An array may be defined as the total set of subclasses produced when a class is divided by a single specific principle, so that the resulting subclasses are mutually exclusive..."

In this tradition Ranganathan proposed his PMEST formula: Personality, Matter, Energy, Space and Time:

B. C. Vickery (1960, p. 12) writes: "The essence of facet analysis is the sorting of terms in a given field of knowledge into homogeneous, mutually exclusive facets, each derived from the parent universe by a single characteristic of division. We may look upon these facets as groups of terms derived by taking each term and defining it, per genus et differentiam, with respect to its parent class......Facet analysis is therefore partly analogous to the traditional rules of logical division, on which classification has always been based....". He also finds that a longer list of fundamental categories has proved helpful in science and technology:

• Substance (product)
• Organ
• Constituent
• Structure
• Shape
• Property
• Object of action (patient, raw material)
• Action
• Operation
• Process
• Agent
• Space
• Time


“As well as these, in any scientific classification there may occur a number of terms applicable at several points in the combination formula. For example, any property or process may itself have a general property: rate, variation, and so on.” (Vickery, 1960. p. 23-24).

Vickery’s expansion of the number of fundamental categories may imply that there is not a fixed set of categories in the world (cf. category).


"Mills (2004, p. 541) writes that he does not see faceted classification as a particular kind of library classification but as the only viable form enabling the locating and relating of information to be optimally predictable. . . .The continued existence of the library as a highly organized information store is assumed." And on p. 547: "The development of logically structured classifications covering the whole of knowledge is still unique in the field of LIS. These provide detailed maps of knowledge to assist in the searching of stores of records and can be used as the basis of, or valuable supplements to, numerous other retrieval languages". 

    While Mills view may basically be right, we find it necessary not to recommend not to consider this tradition in KO alone in LIS-education, but to consider it in the context of other approaches". (Broughton et al., 2005).

Hjørland (1988) suggests that the facets constructed in facetted classification systems like Bliss may in fact be used to construe facets in online searching (at least as a heuristic tool) and he exemplify this with a concrete example from psychology. Curiously enough there have been extremely little exchange of knowledge between the online community and the knowledge organization community in relation to facets and facet analysis. Hjørland's idea has not until  now (2005) been taken up, commented or further considered by other researchers.


Facet analysis may be considered as one approach to knowledge organization among other approaches (cf., approaches to knowledge organization).  The strong and weak aspects of facet analysis should thus be identified in relation to other approaches. To be able to do so library and information researchers must know and have the necessary qualifications in all the major approaches (until now very few researchers have such qualifications). One of the best discussions of this approach is made by Miksa (1998), who raises tree kinds of negative aspects of Ranganathan's work (p. 71-73):

  1. Ranganathan helped to promote the "atomization" of subjects.

  2. Neither Ranganathan himself nor those who have adopted his approach to subjects have ever critically analyzed the analogy at the base of his approach. "In the end, there is strong indication that Ranganathan's use of faceted structure of subjects may well have represented his need to find more order and regularity, in the realm of subjects, than actually exist" (Miksa, 1998, p. 73).

  3. Ranganathan vigorously pursued the goal of finding one best subject classification system


The basic philosophy of facet analysis seems also related to the philosophy of semantic primitives and may thus be founded in a broader theory of semantics.



Application of facet analysis in automatic indexing and on Internet Websites


"For the past ten years DRTC/ISI have had several projects on automatic indexing and automatic classification based on the conceptual principles of faceted classifications by Ranganathan and Bhattacharyya's theory of "deep structure of subject indexing languages". E.g. POPSI (knowledge representation model chosen to support inference rules for syntax synthesis), PROMETHEUS (parses expressive titles and extracts noun phrases within documents which are then processed through a knowledge representation model to generate meaningful strings) and VYASA (a knowledge representation system for automatic maintenance of analytico-synthetic scheme) " Aida Slavic, 2006-09-03, message posted on isko-l@lists.gseis.ucla.edu


La Barre (2006) found that faceted techniques are increasingly being used in the design of web-pages. A specific format, XFML, a simple XML format for exchanging metadata in the form of faceted hierarchies has been developed (Van Dijck, 2003).





Aitchison, J. (1986). A Classification as a Source for a Thesaurus: The Bibliographic Classification of H. E. Bliss as a Source of Thesaurus Terms and Structure. Journal of Documentation, 42(3), 160-181.


Allen, R. B. (1995). Retrieval from facet spaces. Electronic Publishing, 8(2 & 3), 247–257.

http://www.ischool.drexel.edu/faculty/ballen/PAPERS/FACETS/facets.html and http://cajun.cs.nott.ac.uk/compsci/epo/papers/volume8/issue2/2point31.pdf


Anderson, J. D. (1979). Contextual indexing and faceted classification for databases in the humanities. Proceedings of the American Society for Information Science, 16, 194-201.


Batty, D. (1981). Life begins at 40 - the resurgence of facet analysis. Proceedings of the American Society for Information Science, 18, 340-342.  

Beghtol, Clare (2008). From the Universe of Knowledge to the Universe of Concepts: The Structural Revolution in Classification for Information Retrieval. Axiomathes, in press

Broughton, V. (2006). The need for a faceted methods of information retrieval. ASLIB Proceedings, 58(1-2), 49-72.


Broughton, Vanda (2008). A Faceted Classification as the Basis of a Faceted Terminology: Conversion of a Classified Structure to Thesaurus Format in the Bliss Bibliographic Classification, 2nd Edition. Axiomathes, in press


Broughton, V.; Hansson, J.; Hjørland, B. & López-Huertas, M. J. (2005). [Chapter 7:] Knowledge Organization. IN: European Curriculum Reflections on Library and Information Science Education. Ed. by L. Kajberg & L. Lørring. Copenhagen: Royal School of Library and Information Science. (Pp. 133-148). [Report of working group on LIS-education in Europe. Working seminar held  in Copenhagen 11-12 August 2005 at the Royal School of Library and Information Science.] Available: http://biblis.db.dk/uhtbin/hyperion.exe/db.leikaj05

Devadason, F.; Intaraksa, N.; Patamawongjariya, P. & Desai, K. (2001). Search interface design using faceted indexing for Web resources. ASIST 2001: Proceedings of the 64th ASIST Annual Meeting, 38, 224-238.

Devadason, F. J.; Intaraksa, N.; Patamawongjariya, P. & Desai, K. (2002). Faceted indexing based system for organizing and accessing Internet resources. Knowledge Organization, 29(2), 65-77. 

Ellis, D, & Vasconcelos, A. (1999). Ranganathan and the Net: using facet analysis to search and organise the World Wide Web. ASLIB Proceedings, 51(1), 3-10.

Godert, W. (1991). Facet classification in online retrieval. International Classification, 18(2), 98-109.

Harter, S. P. (1986). Online Information Retrieval. Concepts, Principles and Techniques. New York: Academic Press, Inc.


Hearst, M. A. (2006). Clustering versus Faceted Categories for Information Exploration. COMMUNICATIONS OF THE ACM, 49(4), 59-61.  http://web.archive.org/web/20070318090819/http://flamenco.berkeley.edu/papers/cacm06.pdf


Hjørland, B. (1988). Information Retrieval in Psychology. Behavioral and Social Sciences Librarian, 6(3/4), 39‑64. Click for full-text IR in psychol_1988.PDF

Krauth, J. (1981). Techniques of classification in psychology I: factor analysis, facet analyses, multidimensional scaling, latent structure analysis. International Classification, 8(3), 126-132.

La Barre, K. (2006). The use of facetted analytico-synthetic theory as revealed in the practice of website construction and design. Ph.D thesis submitted to the School of Library and Information Science, Indiana University.

Levitt, J. M. (2004). Demonstrating a multi-faceted magpie approach to researching searchable digital text. ASLIB Proceedings, 56(5), 315-320.

Maple, A. (1995). Faceted Access: A Review of the Literature. http://theme.music.indiana.edu/tech_s/mla/facacc.rev

Miksa, F. (1998). The DDC, the Universe of Knowledge, and the Post-Modern Library. Albany, NY: Forest Press.

Miksa, Shawne D.; Burnett, Kathleen;  Bonnici, Laurie J. & Kim,  Joonmin (2007). The Development of a Facet Analysis System to Identify and Measure the Dimensions of Interaction in Online Learning. Journal of the American Society for Information Science & Technology, 58(11), 1569–1577.

Mills, J. (2004). Faceted classification and logical division in information retrieval. Library Trends, 52(3) 541-570.  

Mills, J. & Broughton, V. (1977). Bliss Bibliographic Classification. Second Edition. Introduction and Auxiliary Schedules. London: Butterworth.

Mutrux, R. & Anderson, J. D. (1983). Contextual indexing and faceted taxonomic access system. Drexel Library Quarterly, 19(3), 91-109.

Ranganathan, S. R. (1985). Facet Analysis. Fundamental Categories. IN: Theory of Subject Analysis. Littleton, Colorado,  pp. 86-93).

Slavic, Aida & Cordeiro, Maria Ines (2004). Core requirements for automation of analytico-synthetic classifications. In McIlwaine, I.C., Eds. Proceedings International Society for Knowledge Organization Conference, pages pp. 187-192, London, England.

Spiteri, L. (1998). A simplified model for facet analysis: Ranganathan 101. Canadian Journal of Information and Library Science-Revue Canadienne des Sciences de l'Information et de Bibliotheconomie, 23(1-2), 1-30.

Star, S. L. (1998). Grounded classification: Grounded theory and faceted classification. Library Trends, 47(2), 218-232. 

Svenonius, E. (1978). Facet definition: Case-study. International Classification, 5(3), 134-141.

Taylor, A. G. (1992). Introduction to Cataloging and Classification. 8th ed. Englewood, Colorado: Libraries Unlimited.

Van Dijck, Peter. (2003). Introduction to XFML. xml.com. http://www.xml.com/lpt/a/2003/01/22/xfml.html

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

Vickery, B. C. (2008). Faceted Classification for the Web. Axiomathes, in press

Walker, T. D. (1996). Medieval faceted knowledge of classification: Ramon Llull's trees of science. Knowledge Organization, 23(4), 199-205.

Whitrow, M. (1983). An 18th-century faceted classification-system. Journal of Documentation, 39(2), 88-94.  

Xiao, Y. (1994). Faceted classification - a consideration of its features as a paradigm for knowledge organization. Knowledge Organization, 21(2), 64-68.

Yee, K., Swearingen, K., Li, K., & Hearst, M. (2003). Faceted metadata for image search and browsing. In G. Cockton & P. Korhonen (Eds.), CHI '03: Proceedings of the SIGCHI Conference on Human Factors in Computing Systems (pp. 401-408). New York: ACM Press. http://web.archive.org/web/20060209222202/bailando.sims.berkeley.edu/papers/flamenco-chi03.pdf



See also: Multiple taxonomies


Birger Hjørland

Last edited: 08-03-2008





  1. Discuss the empirical basis (or lack of such) of the facetted approach to knowledge organization: a) Is there an empirical basis? b) is the empirical basis acknowledge in the methodology of facet analysis? c) Is facet-analysis about universal semantic relations beyond any particular empirical domain?  If so d) On what basis are classification systems revised?

  2. The theory of facet-analysis has very seldom been related to broader theories of knowledge and language. Compare it with the linguistic notion of semantic primitives and discuss the implication of this comparison. What is gained by relating those two theories?