IEC 60793-1-40:2024 establishes uniform requirements for measuring the attenuation of optical fibre, thereby assisting in the inspection of fibres and cables for commercial purposes. The technical content of IEC publications is kept under constant review by the IEC. Please make sure. stacles regarding interoperability and compatibility between manufacturers. This work materialized through the development of good practices, procedures and specifications documents, reflecting a certain state of the art at a given time, and the result of a consensus of all stakeholders (op lable. Introducing the BS EN IEC 60793-1-40:2025, a comprehensive standard that provides detailed methodologies for measuring the attenuation of optical fibres. aThe fiber dispersion values are normative, all other values in the table are informative. It covers the environmental and length-related.