This part of IEC/IEEE 62582 contains methods for monitoring the attenuation condition of optical fibres and cables in instrumentation and control systems using optical time domain reflectometer (OTDR) measurements in the detail necessary to produce accurate and reproducible measurements. It includes the requirements for the measurement system and conditions, and the reporting of the measurement results. The different parts of IEC/IEEE 62582 are measurement standards, primarily for use in the management of ageing in initial qualification and after installation. IEC/IEEE 62582-1 includes requirements for the application of the other parts of IEC/IEEE 62582 and some elements which are common to all methods. Information on the role of condition monitoring in qualification of equipment important to safety is found in IEEE Std 323. Detailed descriptions of methods for OTDR measurement of the quality and functionality of fibre optic cables are given in IEC 61280-4-1 for multimode attenuation and in IEC 61280-4-2 for single-mode attenuation.