5 and 85/125 Multimode Fiber Minimum Maximum Attenuation (dB/km) Bandwidth (MHzxkm) 0.85 um 1.30 um 1,000 Chapter 2 For single-mode fibers (S = 1, 2, or 3), the S2 character defines the spec- ified maximum individual-fiber attenuation in the cable. The maximum individual-fiber attenuation at 1.55 um depends on the first character, S. When S = 1, then the 1.55-um attenuation is not specified; when S = 2, then the maximum individual-fiber attenuation at 1.55 um is the same as at 1.30 um, as shown in Table 2-4; when S = 3, then the maximum indi- vidual-fiber attenuation at 1.55 um is 0.10 dB/km less than at 1.30 um. For dispersion-shifted single-mode fibers, which are optimized for use at 1.55 um, S1 = 6 or 7. When S = 6, only the attenuation at 1.30 um is spec- ified; when S = 7, the maximum individual-fiber attenuations at 1.30 and 1.55 um are defined, as shown in Table 2-4. For 50/125 multimode fibers, with S = K, L, or M, the S2 character denotes both the minimum allowable bandwidth (in MHzXkm) and the maximum attenuation (in dB/km). Because of the large number of possible combinations of attenuations and bandwidths at the two wavelengths, only a few of the more common combinations are coded, as shown in Table 2-4. Other combinations not shown are coded as S2 = X. For S = K, only the 0.85-um attenuation and bandwidth values apply (the upper of the two attenuation headings and the left bandwidth column). For S1 = M, both 0.85- and 1.30-um values apply. The code also covers 62.5/125 and 85/125 multimode fibers. As with 50/125 fibers, only a few of the most common attenuation and bandwidth combinations are coded. Combinations not shown in the table are coded S2 = X. For S = P or T, only the 0.85-um val- ues apply. For S = Q or W, the 1.30-um values apply. For S = R or Y, both values apply. 2.2 Fiber Splicing Fiber rolls may be of the order of 2 to 4 km; hence, longer metropolitan or long-haul links will entail splices. Splices are also involved in the building spur to metro access ring. A splice is a semipermanent 