This part of IEC 60793 is applicable to optical fibre types A1a, A1b, and A1d. These fibres are used or can be incorporated in information transmission equipment and optical fibre cables.Type A1a fibre is a 50/125 ìm graded index fibre. Type A1a.1 applies to 50/125 ìm fibre,while A1a.2 and A1a.3 apply to two bandwidth grades of 850 nm laser-optimised 50/125 ìm fibre. Type A1b applies to 62,5/125 ìm graded index fibre and A1d applies to 100/140 ìm graded index fibre.Other applications include, but are not restricted to, the following: short reach, high bit-rate systems in telephony, distribution and local networks carrying data, voice and/or video services;