This object indicates the sign of the data for the falling
threshold, as defined by the cHcAlarmFallingThreshAbsValueLo
and cHcAlarmFallingThreshAbsValueHi objects, as described in
the CHcValueStatus textual convention.
The enumeration 'valueNotAvailable(1)' is not allowed, and
the associated cHcAlarmStatus object cannot be equal to
'active(1)' if this object is set to this value.
This object may not be modified if the associated
cHcAlarmStatus object is equal to active(1).