Nomenclature of magnetic, incommensurate, composition-changed morphotropic, polytype, transient-structural and quasicrystalline phases undergoing phase transitions. II. Report of an IUCr Working Group on Phase Transition NomenclatureEstablished 15 February 1994 by the IUCr Commission on Crystallographic Nomenclature; following the resignation of two members upon acceptance of the first Report, three new members were appointed 18 July 1998. This second Report was received by the Commission 26 February 2001 and accepted 19 April 2001. The present Report, as all other Reports of the Commission, is available online at the Commission's webpage: http://www.iucr.org/iucr-top/comm/cnom.html.