EXFO FTB-800 Series for FTB-1 - Manual (Page 324)

Test Results
314 FTB-700G/800 Series
Performance Monitoring

SEP (Severely Errored Period) (G.828 only): A sequence between 3 to
9 consecutive SES. The sequence is terminated by a second which is
not a SES.

SEPI (Severely Errored Period Intensity) (G.828 only): Gives the count
of SEP events in available time, divided by the total available time in
seconds.
Far-End

EFS (Error Free Second): Gives the count of the seconds within which
no error occurred or when a defect is detected on the near-end.

EC (Error Count) (G.821 only): Gives the number of bit errors.

EB (Errored Block) (G.826, G.828, and G.829): Gives the count of
blocks in which one or more bits are in error.

ES (Errored Second): For G.826, G.828, G.829, M.2100 ISM, and
M.2101: Gives the count of the seconds within which one or more
anomalies (FAS (DSn/PDH), EB, etc.) occurred or at least one defect
occurred.

SES (Severely Errored Second)
For G.826, G.828, G.829 and M.2101: Gives the number of seconds
within which anomalies (FAS (DSn/PDH), EB, etc.) are  X% or at least
one defect occurred. X = 30% for DSn/PDH signals; see the following
table for SONET/SDH signals SES threshold.
OC-1
STS-1e
STM-0
STM-0e
OC-3
STS-3e
STM-1
STM-1e
OC-12
STM-4
OC-48
STM-16
OC-192
STM-64
Path 30% 30% 30% 30% 30%
Line/MS 15% 15% 25% 30% 30%
Section/RS 10% 30% 30% 30% 30%