Valid values are:
- "FACILITY_LOOPBACK"
- "TERMINAL_LOOPBACK"
- "FACILITY_FORCED_AIS"
- "TERMINAL_FORCED_AIS"
- "FORCE_RDI"
- "SET_AS_SEGMENT_END_POINT" (ATM)
- "END_TO_END_LOOPBACK_OAM_CELL" (ATM)
- "SEGMENT_LOOPBACK_OAM_CELL" (ATM)
- "LOCAL_LOOP_QUALIFICATION" (DSL)
- "DSL_LINE_SUPERVISION" (DSL)

Refer to associated supporting document maintenanceCommands for an explanation of the maintenance commands.

Readable by NMS? Yes
Writeable by NMS? No
Invariant? Yes
