EXFO FTB-8510B Guia Del Usuario página 811

SM: The Section Monitoring contains the following bytes.
The first SM byte (Column 8) contains the TTI multiframe byte that is
only configurable from OTU TTI TX on page 162.
The second SM byte (Column 9) contains the BIP-8 byte that is
automatically generated for each frame. This byte is not configurable.
The third SM byte (Column 10) contains the following sub-fields. This
byte is configurable from 00 to FF. The default value is 00.
BEI/BIAE
BDI
IAE
RES
GCC0: The two General Communication Channel-0 bytes are
configurable from 00 to FF. The default value for each byte is 00.
RES: The two Reserved (RES) bytes are configurable from 00 to FF. The
default value for each byte is 00.
Default
Reverts the overhead bytes to their default values.
SONET/SDH Application
Sub-field Bit
1-4
5
6
7-8
OTN Tabs
OTU OH TX
161