“…If the phase crystallizes with a standard structure type [for nomenclature and de®nitions of isotypism, see the IUCr Commission Report by Lima-de-Faria et al (1990); for a handbook listing inorganic structure types, see TYPIX by Parthe  et al (1993Parthe  et al ( , 1994; for a corresponding PC database, see TYPIX 1995 by Cenzual et al (1995); and for a recent proposal that applies structuretype formulas to all inorganic materials, see Smith et al (1998)], then the sixth ®eld should begin with an entry in the format |Type = XXXX. Typical structure-type names are, for instance, XXXX = NaCl, pyrite, sphalerite etc., with the name in italics, or, alternatively, structure-type formulas such as XXXX = GXX H , T3(T H /L)X4 etc., with the formula in italics.…”