1.1 This part of ISO 20029 establishes a system of designation for thermoplastic polyester/ester and polyether/ester elastomers, which may be used as the basis for specifications. 1.2 The types of thermoplastic polyester/ester and polyether/ester elastomer are differentiated from each other by a classification system based on appropriate levels of the designatory properties a) hardness; b) melting temperature; c) tensile/flexural modulus of elasticity; and on information about the intended application and/or method of processing, important properties, additives, colour, fillers and reinforcing materials. 1.3 This designation system is applicable to all thermoplastic polyester/ester and polyether/ester elastomers. It applies to materials ready for normal use in the form of powder, granules or pellets, unmodified or modified by colourants, fillers or other additives. 1.4 One should not assume that materials having the same designation give the same performance. This part of ISO 20029 1 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 ISO 20029 2, if suitable. 1.5 In order to designate a thermoplastic polyester/ester or polyether/ester elastomer to meet particular specifications, the requirements are to be given in data block 5 (see 3.1).