This part of IEC 60794 describes test procedures to be used in establishing uniform requirements for optical fibre cables for the environmental property- pneumatic resistance, for unfilled cables which are protected by gas pressurization. This document applies to optical fibre cables for use with telecommunication equipment and devices employing similar techniques, and to cables having a combination of both optical fibres and electrical conductors. NOTE Throughout the document, the wording "optical cable" can also include optical fibre units, microduct fibre units, etc.