This part of EN ISO 8257 establishes a system of designation for poly(methyl methacrylate) (PMMA) thermoplastic materials, which may be used as the basis for specifications.The types of PMMA plastics are differentiated from each other by the classification system based onappropriate levels of the designatory properties:a) Vicat softening temperature,b) melt mass-flow rate,c) viscosity number (optional),and on information about intended application and/or method of processing, important properties, additives and colorants.