Establishes a system of designation for polyoxymethylene (POM) thermoplastic materials, which may be used as the basis for specifications. 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[2]O - as an integral part of the main polymer chain resulting from polymerization of formaldehyde.