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 µm graded index fibre. Type A1a.1 applies to 50/125 µm fibre, while A1a.2 and A1a.3 apply to two bandwidth grades of 850 nm laser-optimised 50/125 µm fibre. Type A1b applies to 62,5/125 µm graded index fibre and A1d applies to 100/140 µm 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; on-premises intra-building and inter-building fibre installations including Data Centres, LANs, Storage Area Networks, PBXs, video, various multiplexing uses, outside telephone cable plant use, and miscellaneous related uses. Three types of requirements apply to these fibres: – general requirements, as defined in IEC 60793-2; – specific requirements common to the category A1 multimode fibres covered in this standard and which are given in Clause 3; – particular requirements applicable to individual fibre types or specific applications, which are defined in the normative family specification annexes.