This document establishes a system of designation for polyoxymethylene (POM) thermoplastic material, which can be used as the basis for specifications. NOTE Polyoxymethylene materials are thermoplastic materials composed principally of long-chain synthetic homopolymers and copolymers of formaldehyde. The repeating unit in the molecular chain is – CH 2O – as an integral part of the main polymer chain resulting from polymerization of formaldehyde.The types of polyoxymethylene plastic are differentiated from each other by a classification system based on appropriate levels of the following designatory properties: melt mass-flow rate or melt volume-flow rate; tensile modulus, and on information about basic polymer parameters, intended application, method of processing, important properties, additives, colorants, fillers and reinforcing materials. This document is applicable to all polyoxymethylene homopolymers and to copolymers of polyoxymethylene and blends of polymers containing polyoxymethylene. It applies to materials ready for normal use in the form of powder, granules or pellets and to materials unmodified and modified by colorants, additives, fillers, etc. It is not intended to imply that materials having the same designation necessarily give the same performance.This document does not provide engineering data, performance data or data on processing conditions which can be required to specify materials for particular end-use applications. If such additional properties are required, they are to be determined in accordance with the test methods specified by the relevant International Standard.