This object specifies the value of sysUpTime at the last time
there was either a change to any object in any entry in
nmsifthIfThresholdFiredTable, or an entry was added or deleted in
nmsifthIfThresholdFiredTable. If no change to
nmsifthIfThresholdFiredTable has occurred since the last
re-initialization of the local network management subsystem,
then this object contains a zero value.