Relevant to, in conjunction with the other parts of ISO 21003, to multilayer piping systems intended to be used for hot and cold water installations inside buildings for the conveyance of water - whether or not the water is intended for human consumption (domestic systems) or for heating systems - under specified design pressures and temperatures appropriate to the class of application. Also provides guidance for the assessment of conformity, to be included in the manufacturer's quality plan as part of the quality system.