1.1 Product definition This standard contains the initial, start of life dimensional, optical, mechanical and environmental performance requirements that an assembled singlemode patch cord with cylindrical ferruled connectors shall meet in order for it to be categorised as an EN standard product. Since different variants and grades of performance are permitted, product marking details are given in 3.4 and Clause 4. 1.2 Intermateability of the plugs Although all products conforming to the requirements of this standard will intermate, the resulting level of random attenuation performance will only be ensured in accordance with Table 1. The intention is that this will be true irrespective of the manufacturing source(s) of the product. When intermating plug variants having different attenuation grades as specified in EN 61755-1, the resulting level of attenuation cannot be assured to be any better than the worst attenuation grade. The intermating of a grade C plug with a grade B plug will result in a grade C level of random attenuation performance. Table 1 - Ensured level of random attenuation