IEC 60793-2-50:2025 is applicable to optical fibre categories B-652, B-653, B-654, B-655, B‑656 and B-657. A map illustrating the connection of IEC designations to ITU-T designations is shown in Table 1. These fibres are used or can be incorporated in information transmission equipment and optical fibre cables. Three types of requirements apply to these fibres:
- general requirements, as defined in IEC 60793-2;
- specific requirements common to the class B single-mode fibres covered in this document and which are given in Clause 4;
- particular requirements applicable to individual fibre categories or specific applications, which are defined in Annex A to Annex F.
For some fibre categories (shown in the relevant family specifications), there are sub-categories that are distinguished on the basis of difference in transmission attribute specifications. The designations for these sub-categories are documented in the individual family specifications. Table 1 shows a map from the IEC designations to the ITU-T recommendations.
This seventh edition cancels and replaces the sixth edition published in 2018. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition.
a) The addition of a 200 µm coating nominal outer diameter option for B-654A, B, C fibres in Annex C