EXFO FTB/IQS-88000 Series Power Blazer for FTB-2/2Pro/500/IQS-600 - Manual (Page 311)

Test Results
Power Blazer 299
Alarms/Errors

C-RDI (Client Signal Fail - Remote Defect Indication)
RX: A CSF frame is received with CSF type equal to 010. The alarm is
cleared when no CSF (C-RDI) frames are received during an interval
equal to 3.5 times the CSF transmission period indicated in the last
received CSF (C-RDI) frame, or when a CSF frame is received with
Client Defect Clear Indication (C-DCI) information (CSF Type 011).
TX: Generates a CSF frame with CSF type equal to 010.

C-DCI (Client Signal Fail - Defect Clear Indication)
TX: Generates a CSF frame with CSF type equal to 011.