This notification indicates that the EFMCu port's data rate has reached/dropped below or exceeded the low rate threshold, specified by efmCuThreshLowRate. This notification MAY be sent for the -O subtype ports (2BaseTL-O/10PassTS-O) while the port is Up, on the crossing event in both directions: from normal (rate is above the threshold) to low (rate equals the threshold or below it) and from low to normal. This notification is not applicable to the -R subtypes. It is RECOMMENDED that a small debouncing period of 2.5 sec, between the detection of the condition and the notification, is implemented to prevent simultaneous LinkUp/LinkDown and efmCuLowRateCrossing notifications to be sent. The adaptive nature of the EFMCu technology allows the port to adapt itself to the changes in the copper environment, e.g., an impulse noise, alien crosstalk, or a micro-interruption may temporarily drop one or more PMEs in the aggregation group, causing a rate degradation of the aggregated EFMCu link. The dropped PMEs would then try to re-initialize, possibly at a lower rate than before, adjusting the rate to provide required target SNR margin. Generation of this notification is controlled by the efmCuLowRateCrossingEnable object.