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 categorised as meeting the IEC standard. The requirements cover balanced bidirectional non-connectorised single-mode 1×N and 2×N non-wavelength-selective branching devices for use in an IEC Category C environment (N is the number of branching ports), especially but not exclusively used for PON application. For balanced NWBD two attenuation and uniformity performance classes are considered: Class A (premium class) which meets more restrictive requirements (i.e. for extended reach PON application) and Class B (standard class) for standard application (i.e. normal reach PON application) . The requirements also cover unbalanced bidirectional non-connectorized single-mode non wavelength-selective branching devices, however the specifications of unbalanced branching devices are limited to 1x2 and 2x2 devices because they are the most commonly used .