This part of IEC 60793-2 is applicable to optical fibre categories A4a, A4b, A4c, A4d, A4e, A4f, A4g and A4h. These fibres have a plastic core and plastic cladding and may have stepindex, multi-step index, or graded-index profiles. The fibres are used in information transmission equipment and optical fibre cables. Table 1 summarizes some of the salient characteristics and applications of these fibres. Table 1 – Characteristics and applications of category A4 Fibres A4a A4b A4c A4d A4e A4f A4g A4h Core diameter (μm) See Note 1 See Note 1 See Note 1 See Note 1 ≥500 200 120 62,5 Cladding diameter (μm) 1000 750 500 1000 750 490 490 245 Numerical aperture 0,50t 0,50t 0,50t 0,30t 0,25t 0,190e 0,190e 0,190e Operating wavelength(s) (nm) 650 See Note 2 650 650 650 650 650, 850, 1300 650, 850, 1300 850, 1300 Applications Digital audio interface, automobile, industrial and sensor Data transmission industrial and sensor sensor Digital audiovisual interface and data transmission Digital audiovisual interface and data transmission Industrial and mobile; compatible with A3 transmission equipment Data transmission Data transmission; primarily used in ribbon structures NOTE 1 Typically 15μm to 35 μm smaller than the cladding diameter. NOTE 2 Other potential wavelengths for A4a fibre are described in Annex J. t Theoretical. e Measured effective. In addition to the applications shown in Table 1, other applications for A4 fibres include, but are not restricted to, the following: support for short reach high bit-rate systems in telephony, distribution and local networks, carrying data, voice and/or video services and on-premises intrabuilding and interbuilding fibre installations, including LANs, PBXs, video, various multiplexing uses, and miscellaneous related uses, such as consumer electronics and industrial and mobile networks. Three types of requirements apply to A4 fibres: general requirements, as defined in IEC 60793-2; specific requirements common to category A4 multimode fibres covered in this standard and that are given in Clause 3; particular requirements applicable to individual fibre types or specific applications and that are defined in this standard in the normative family specification annexes.