The first"Manual of Symbols and Terminology for Physicochemical Quantities and Units"(the 'Green Book'), of which this is a direct successor, was published in 1969, with the objective of securing clarity and precision, and wider agreement in the use of symbols, by chemists in different countries, among physicists, chemists and engineers, and by editors of scientific journals. Subsequent editions of this book and of"Quantities, Units and Symbols in Physical Chemistry"have been substantially revised and extended, containing many new resolutions and recommendations from Conference Generale des Poids et Mesures, International Union of Pure and Physics, the International"