Glossary · Information modeling

Faceted classification

Also known as: Facet analysis, Facet (classification), Analytico-synthetic classification

German: Facettenklassifikation

In knowledge organization, faceted classification describes a subject by combining values from several independent facets — such as product, component, task, audience and life-cycle phase — instead of placing it at one point in a single hierarchy; it was developed by the Indian librarian S. R. Ranganathan from 1933.

Information architecture
Ontology

In one sentence

Faceted classification describes content by combining values from independent facets instead of one hierarchy — after S. R. Ranganathan (1933).

Example

A topic is classified as product “PM-200”, component “sealing unit”, information type “task”, phase “maintenance”, audience “service technician”. Readers can filter by any facet; a single folder tree would force one of them to come first.

How it applies

Ranganathan’s scheme: The Colon Classification (1933) built class numbers by combining facets, joined by punctuation such as the colon. Ranganathan later generalized the facets into five fundamental categories: Personality, Matter, Energy, Space and Time (PMEST).
Analytico-synthetic: Facet analysis first breaks a subject field into mutually exclusive facets and their values (analysis), then builds the description of an item by combining them (synthesis). The UK Classification Research Group developed the method further from 1952.
In digital systems: Faceted search and filtering in online help, e-commerce and content delivery portals apply the same idea; the facets become metadata fields with controlled values.
Technical documentation: Metadata models for technical documentation — iiRDS among them — are largely faceted: product, component, information type, life-cycle phase, audience. Keeping the facets independent (a value of one facet never implies a value of another) is what makes filtering reliable.

Faceted classification vs. taxonomy

A taxonomy arranges concepts in one hierarchy of broader and narrower terms; a faceted scheme uses several smaller hierarchies, one per facet, and combines them. Each facet can itself be a taxonomy.