EXFO FTB-8510B Guia Del Usuario página 1157

For M.2100 ISM: Gives the count of the seconds within which
anomalies (frame bit errors, CRC block errors, etc.) are ≥ Y or at least
one defect occurred. Y depends on the type of DSn/PDH signal as
described in the following table.
Signal
DS1 (SF)
DS1 (ESF)
E1 (Framed without CRC-4) 28 frame bit errors (Near-End)
E1 (Framed with CRC-4)
DS3 (M13)
DS3 (C-bit Parity)
E2 (Framed)
E3 (Framed)
E4 (Framed)
SONET/SDH Application
8 frame bit errors (Near-End)
320 CRC-6 block errors (Near-End) 320 CRC-6 block errors
(Far-End, if FDL enabled)
805 CRC-4 block errors (Near-End) 805 E-bit errors
(Far-End)
2444 P-bit errors (Near-End) or 5 F-bit errors (Near-End)
2444 P-bit errors (Near-End) or 5 F-bit errors
(Near-End) 2444 FEBE errors (Far-End)
41 frame bit errors (Near-End)
52 frame bit errors (Near-End)
69 frame bit errors (Near-End)
Performance Monitoring (PM)
SES Threshold
Common Tabs
507