1.1 This part of ISO 28078 establishes a system of designation for PPS thermoplastic materials, which may be used as the basis for specifications. 1.2 The types of PPS plastic are differentiated from each other by a classification system based on appropriate levels of the designatory properties a) melt mass-flow rate or melt viscosity b) density c) tensile modulus and on information about the intended application and/or method of processing, important properties, additives, colorants, fillers and reinforcing materials. 1.3 This part of ISO 28078 is applicable to all PPS materials. 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 It is not intended to imply that materials having the same designation necessarily have the same performance. This part of ISO 28078 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 ISO 28078-2, 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 3.1).