“For federal agencies trying to learn how to implement taxonomies, most examples in portals and on public websites are informal taxonomies where neither the nodes nor the associations between them are formally defined. Examples of such taxonomies can be found on yahoo.com, froogle.com, and dmoz.org. Such informal taxonomies are only useful for browsing and not for automated techniques like query expansion, rule execution, taxonomy integration, faceted classification, and inference. This article will examine the requirements of formal taxonomies and provide examples of each construct.” (Michael Daconta – xml.com)