EXFO FTB-800 Series for FTB-1 - Manual (Page 410)

Test Functions
400 FTB-700G/800 Series
FDL - Performance Report Message

Performance Information table, available when the Report Content
button is selected, reports the time t0, t0-1, t0-2, and t0-3 for each PRM.
Time

T0 represents the valid PRM message received in the last second of
measurement (bytes 5 and 6).

T0-1 represents the message one PRM ago (bytes 7 and 8).

T0-2 represents the message two PRM ago (bytes 9 and 10).

T0-3 represents the message three PRM ago (bytes 11 and 12).
PRM
G3: 5 < CRC Error Event 10
LV: Line Code Violation Event  1
G4: 10 < CRC Error Event  100
U1: Under study for synchronization
U2: Under study for synchronization
G5: 100 < CRC Error Event 319
SL: Controlled Slip Event  1
G6: CRC Error Event  320
FE: Frame Sync. Bit Error Event  1
SE: Severely-Errored Framing Event  1
LB: Payload Loopback Activated
G1: CRC Error Event = 1
R: Reserved
G2: 1 < CRC Error Event  5
Nm and Nl: One-second report modulo 4 counter.