This value represents the Physical Link hardware
controller mode for the line device. The values
for controller-mode are:
NORMAL For normal controller operating mode.
LOOPBACK For software controllable loopback of the
controller. On those devices that can support this
mode, it causes all transmitted messages to be looped
back from within the controller itself. This is
accomplished without any manual intervention other
than the setting of this parameter value.
OTHER indicates function is not supported
Note that these values are incremented by one compared to
the standard DECnet values.