IEC/TR 62627-04:2012(E) represents a selected example that concerns the measurement of the attenuation of passive optical components (IEC 61300-3-4), particularly focussed on insertion method B for low-loss optical connectors assembled on SM optical fibre (according to IEC 60793-2-50, Type B1.3). Keywords: measurement of the attenuation of passive optical components (IEC 61300-3-4)