DANSK DS/EN 50377-11-1 PDF

1.1 Product definition
This specification contains the initial, start of life dimensional, optical, mechanical and environmental performance requirements which a terminated and assembled singlemode MF 4-fold-connector set (for backplane applications) must 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 3.5.
1.2 Intermateability
Although all products conforming to the requirements of this standard will inter mate, 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 inter mating plug variants having different attenuation grades, the resulting level of attenuation can not be assured to be any better than the worst attenuation grade.
The inter mating of a grade C plug with a grade B plug will result in an uncertain level of random attenuation performance.