This variable indicates what type of code is
being sent across the DS1 circuit by the CSU. The
values mean:
ds3SendNoCode
sending looped or normal data
ds3SendSetCode
sending a loopback request
ds3SendLoopbackCode
sending the code to choose a specific
loopback
ds3SendResetCode
sending a loopback termination request
ds3SendTestMessage
sending a Test pattern as defined in
T1.107a-1989 [10a].