This flag tells the device whether to treat the alarm entry's lifetime as unlimited (forever) or bounded by the hh3cRmonExtAlarmStatCycle value (during). It works together with the stat-cycle field: setting this to during is what actually activates the expiration timer, while forever, the default, means the cycle value is ignored and the entry persists until manually deleted. For a temporary week-long diagnostic alarm, an admin would set this to during so the paired stat-cycle value takes effect.