This part of IEC 61757 is a generic specification covering optical fibres@ components and subassemblies as they pertain specifically to fibre optic sensing applications. It has been designed to be used as a common working and discussion tool by the vendor of components and subassemblies intended to be integrated in fibre optic sensors@ as well as by designers@ manufacturers and users of fibre optic sensors independent of any application or installation. The objective of this generic specification is to define@ classify and provide the framework for specifying fibre optic sensors@ and their specific components and subassemblies. The requirements of this standard apply to all related sectional@ family@ and detail specifications. Sectional specifications will contain requirements specific to sensors for particular quantities subject to measurement. Within each sectional specification@ family and detail specifications contain requirements for a particular style or variant of a fibre optic sensor of that sectional specification. A fibre optic sensor contains an optical or optically powered sensing element in which the information is created by reaction of light to a measurand. The sensing element can be the fibre itself or an optically powered element inserted along the optical path. In a fibre optic sensor@ one or more light parameters are directly or indirectly modified by the measurand somewhere in the optical path@ contrary to an optical data link where the information is merely transmitted from the transmitter to the receiver. Generic tests or measurement methods are defined for specified attributes. Where possible@ these definitions are by reference to an IEC standard ?C otherwise the test or measurement method is outlined in the relevant sectional@ family and/or detail specification. Annex A gives examples of fibre optic sensors to better illustrate the classification scheme. The examples given are illustrative only and are not limitative@ nor do they constitute a recommendation or endorsement of a particular transduction principle.