The measured object. This is the object name of the object in the MIB with which the alarm is associated and which the configured thresholds are compared with when deriving the state of the alarm. It is not neccessary for all alarm measurement values to be identified in the MIB since a single alarm may be dependant on checks against entities or objects which are not present in the MIB and therefore do not have an associated OID. In general where an alarm and its thresholds relate to the monitoring of the value of a single MIB object then the OID of that object will be defined here otherwise the value is set to empty string.