Applicable to the single-phase connection assemblies between gas-insulated metal-enclosed switchgear for rated voltages of 72,5 kV and above satisfying the requirements of IEC 60517 and power transformers satisfying the requirements of IEC 60076 and fitted with completely immersed bushings satisfying the requirements of IEC 60137, one end of which is immersed in the transformer oil, and the other end in the insulating gas of the switchgear. Its purpose is to establish electrical and mechanical interchangeability in the interface arrangement of these connection assemblies and to determine the limits of supply.