1.1 This part of ISO 15023 establishes a system of designation for poly(vinyl alcohol) (PVAL) materials which may be used as the basis for specifications. 1.2 The types of poly(vinyl alcohol) (PVAL) materials are differentiated from each other by a classification system based on the designatory properties: a) degree of hydrolysis b) viscosity of aqueous solution under defined conditions and on information about basic polymer parameters, intended application and/or method of processing, important properties, additives, colorants, fillers and reinforcing materials. 1.3 This part of ISO 15023 is applicable to all poly(vinyl alcohol) (PVAL) materials with a degree of hydrolysis not less than 70 mol%. It applies to materials ready for normal use in the form of powder, granules or pellets, and to materials unmodified or modified by colorants, additives, fillers, etc. 1.4 One should not assume that materials having the same designation give the same performance. This part of ISO 15023 does not provide engineering data, performance data or data on processing conditions which may be required to specify a material. 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 designate a thermoplastic material to meet particular specifications, the requirements are to be given in data block 5 (see 3.1).