This part of IEC 60794-1 defines test procedures to be used in establishing uniform requirements for the environmental performance of " optical fibre cables for use with telecommunication equipment and devices employing similar techniques, and " cables having a combination of both optical fibres and electrical conductors. Throughout this document, the wording "optical cable" can also include optical fibre units, microduct fibre units, etc. This document defines a test standard to determine the ability of a cable to withstand the effects of temperature cycling by observing changes in attenuation. See IEC 60794-1-2 for a reference guide to test methods of all types and for general requirements and definitions.