This read-write Integer32 (1 to 100), applicable only when the flow is monitored via Y.1731 ESA functionality, sets the frame-loss-ratio percentage threshold at which counting of a Severely Errored Second (SES) begins on the Ethernet Flow. It defines the sensitivity of Y.1731-based SES counting used for SLA and performance monitoring on the flow. For example, an administrator sets the SES threshold ratio to 30 percent, so any one-second interval losing more than 30 percent of frames counts as a Severely Errored Second under Y.1731 ESA monitoring.