This part of ISO 16396 establishes a system of designation for polyamide (PA) moulding and extrusion materials, which can be used as the basis for specifications.The types of polyamide plastics are differentiated from each other by a classification system based on appropriate levels of the designatory propertiesa) viscosity number andb) tensile modulus of elasticityand on information about composition, intended application and/or method of processing, important properties, additives, colorants, fillers, and reinforcing materials.The designation system is applicable to all polyamide homopolymers, copolymers, and blends.It applies to unmodified materials ready for normal use and materials modified, for example, by colorants, additives, fillers, reinforcing materials, and polymer modifiers.This part of ISO 16396 does not apply to the following materials:a) monomer casting-type polyamides of PA 6;b) monomer casting-type polyamides of PA 12.It is not intended to imply that materials having the same designation give the same performance. This part of ISO 16396 does not provide engineering data, performance data, or data on processing conditions which can be required to specify a material. If such additional properties are required, they will be determined in accordance with the test methods specified in ISO 1874-2, if suitable.In order to designate a thermoplastic material to meet particular specifications, the requirements are to be given in data block 5 (see 3.1).