This document specifies the designation system for ethylene-vinyl alcohol (EVOH) copolymer thermoplastic materials, and the system can be used as the basis for classification. Different types of ethylene-vinyl alcohol (EVOH) copolymer thermoplastic materials are distinguished with a classification system based on the following specified properties, such as melt mass-flow rate, together with recommended use and/or processing methods, important properties, additives, colorants, fillers, and reinforcing materials. This document applies to copolymers of ethylene and vinyl alcohol with an ethylene content (mol fraction) of 15%~60%. This document applies to materials that are conventionally in the form of powders, granules or pellets, unmodified or modified by colorants, additives, fillers, etc. This document does not imply that identically named materials will necessarily have identical properties. This document does not provide engineering data, performance data, or processing condition data necessary to describe a particular application and/or processing method for the material. If necessary, the test methods specified in GB/T 41877.2 are used to determine the additional information. In order to illustrate the special use of thermoplastic materials or to ensure the reproducibility of processing, additional information may be given in data blocks 4 and 5 (see Chapter 4).