BS EN 61753-031-3. Fibre optic interconnecting devices & passive components. Performance standard. Part 31-3. Non-connectorised single-mode 1x N & 2x N non-wavelength-selective branching devices for Category U. Uncontrolled environment Fibre optic connectors, Fibre optic branching devices, Fibre optics, Performance, Optical communication systems, Interfaces, Electronic equipment & components, Environmental testing, Electrical testing, Performance testing,