Facet, Facet Analysis and Facet-Analytic Theory

S. R. Ranganathan is credited with introducing the facet-analytic approach to subject analysis and knowledge organisation. It has been the single most important development impacting information retrieval tools and technologies at least since the middle of the 20th Century. The British Classification Research Group (CRG) issued a manifesto in 1955 suggesting that faceted classification should be the basis of all information retrieval. The manifesto also suggested that Facet Analysis should be viewed as a general methodology for the design of systems of knowledge organisation. The notion of Facetis central to Facet Analysis and any theory of faceted classification. While the notions of Facets and Facet Analysis have been with us for nearly a century, there is still no universally accepted standard use of these notions. Is the facet-analytic approach a theory or is it primarily a methodology? Clear and distinct definition and uniform use of the notions central to any approach are not merely desirable but constitute an essential requirement for developing a general theory of Facet Analysis and faceted classification. It is questionable whether such clear definitions of the central concepts that govern the faceted approach exist. This paper examines the use of the notion of ‘Facets’  including inconsistencies  in its application and suggests a definition of the term ‘Facet’. The scope is largely limited to examination of the use and application of the terms in the writings of Ranganathan, his associates, and members of the CRG. However, references to comparatively more recent papers have been made. The objective is to define Facet, Facet Analysis, and explain the facet-analytic approach to a theory of knowledge organisation.