This part of the standard applies to fibre optic attenuators which have all of the following general features: they are passive in that they contain non optoelectronic or other transducing elements; they have two ports for the transmission of optical power, and attenuate the transmitted power in a fixed or variable fashion; the ports are optical fibres or optical fibre connectors. It establishes uniform requirements for the following: optical, mechanical and environmental properties, and measurement and test porcedures for quality assessment.