This part of IEC 61753 contains the minimum initial tests and measurement requirements and severities which a non-wavelength selective branching device (NWBD) should satisfy in order to be categorized as meeting the requirements of Category U (uncontrolled environment) as defined in Annex A of IEC 61753-1. This standard takes into account two technologies present on the market: the Fused Biconical Taper (FBT) and the Planar Lightwave Circuit (PLC). Requirements cover balanced, bidirectional, non-connectorized, single-mode 1 × N and 2 × N non-wavelength-selective branching devices for use in an IEC Category U environment (N is the number of output ports), especially for Passive Optical Network (PON) application. The specifications of unbalanced branching devices are limited to 1 × 2 and 2 × 2 devices because they are the most commonly used.