Taxonomy lies at the uneasy interface between biology and logic. The processing of information follows somewhat different rules in these two systems and the role of taxonomy is to reconcile them as tidily as possible. To this end, the International Union of Microbiological Societies (IUMS) charged the International Committee on Taxonomy of Viruses (ICTV) with the task of developing, refining, and maintaining a universal virus taxonomy. The goal of this undertaking is to categorize the multitude of known viruses into a single classification scheme that reflects their evolutionary relationships, i.e. their individual phylogenies. The most recent report of the ICTV: "Virus Taxonomy: VIIIth Report of the International Committee on Taxonomy of Viruses", 2005, C.M. Fauquet, M.A. Mayo, J. Maniloff, U. Desselberger, and L.A. Ball (Eds), Elsevier Academic Press, is the standard and definitive reference for virus taxonomy.