1 .l This part of IS0 4894 establishes a system of designation for styrene/acrylonitrile thermoplastic material, which may be used as the basis for specifications. 1.2 The types of styrene/actylonitrile plastic are differentiated from each other by a classification system based on appropriate levels of the designatory properties a) Vicat softening temperature b) melt flow rate and on information about basic polymer parameters, intended application and/or method of processing, important properties, additives, colourants, fillers and reinforcing materials. 1.3 This part of IS0 4894 is applicable to all copolymers of styrene and/or substituted styrene having between 10 % (m/m) and 50 % (m/m) acrylonitrile. It applies to materials ready for normal use and to materials unmodified or modified by colourants, additives, fillers, etc. 1.4 It is not intended to imply that materials having the same designation give necessarily the same performance. This part of IS0 4894 does not provide engineering data, performance data or data on processing conditions which may be required to specify a material for a particular application and/or method of processing. If such additional properties are required, they shall be determined in accordance with the test methods specified in part 2 of this International Standard, if suitable. 1.5 In order to specify a thermoplastic material for a particular application or to ensure reproducible processing, additional requirements may be given in data block 5 (see clause 3, introductory paragraph).