This part of IEC 60794 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, " cables having a combination of both optical fibres and electrical conductors. Throughout the standard the wording optical cable may also include optical fibre units, microduct fibre units, etc. See IEC 60794-1-2 for a reference guide to test methods of all types and for general requirements and definitions.