The present document specifies the minimum performance parameters for terrestrial digital fixed service radio communications equipments operating in the 23 GHz frequency band and contains a complete revision in the areas of: - additional systems with higher spectrum efficiency in the new class 4 systems; - introduction of unique system type codes for regulatory reference to the various system types detailed in the present document, refer to annex C and related categories of equipment classes of spectral efficiency; - change of spectrum mask and adjacent channel selectivity of STM-0 systems in 28 MHz channel spacing to align to EN 300 639 [32]; - introductio