IEC 60793-2-20:20 15(E)适用于A2a、A2b和A2c子类别。这些光纤用于或可并入信息传输设备和光缆（通常长达2公里）中。三种类型的要求适用于这些纤维: -IEC 60793-2中定义的一般要求； -本标准涵盖的A2类多模态纤维共有的具体要求，在第3条中给出； -适用于单个子类别或特定应用的特殊要求，在规范性系列规范附件中定义。第三版取消并取代了2007年出版的第二版。本版构成技术修订版。与上一版相比，此版本包括以下重大技术变更:-Nath已被NAff取代； -芯直径和NAff测量的规定试样长度和测量细节。 关键词:信息传输设备光缆A2类多模光纤

IEC 60793-2-20:2015(E) is applicable to sub-categories A2a, A2b, and A2c. These fibres are used or can be incorporated in information transmission equipment and optical fibre cables (typically up to 2 km). Three types of requirements apply to these fibres:
- general requirements as defined in IEC 60793-2;
- specific requirements common to the category A2 multimodal fibres covered in this standard and which are given in Clause 3;
- particular requirements applicable to individual sub-categories or specific applications, which are defined in the normative family specification annexes. This third edition cancels and replaces the second edition, published in 2007. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- Na_th has been replaced by NA_ff;
- specified test specimen length and measurement details for core diameter and NA_ff measurements. Keywords: information transmission equipment, optical fibre cables, category A2 multimodal fibres