EXFO IQS-8100 Series Transport Blazer for IQS-600 - Manual (Page 337)

SDH Tabs
SONET/SDH Application 323
Multiplex Section RX (SDH)
For STM-4: The MS-REI error is declared when the M1 byte located in
the STM-1 channel 3 (timeslot #7) indicates that one or more BIP
violations have been detected.
For STM-16: The MS-REI error is declared when the M1 byte located in
the STM-1 channel 3 (timeslot #7) indicates that one or more BIP
violations have been detected.
M1, bits
234 5678
Indicates
000 0000 0 BIP violation
000 0001 1 BIP violation
000 0010 2 BIP violations
: :
110 0000 96 BIP violations
110 0001 0 BIP violation
: :
111 1111 0 BIP violation
M1 Indicates
0000 0000 0 BIP violation
0000 0001 1 BIP violation
0000 0010 2 BIP violations
: :
1111 1111 255 BIP violations