This read-write INTEGER selects the monitoring interval used for a threshold crossing alert entry, with values duration-15m(1) for a 15-minute interval, duration-1day(2) for a 1-day interval, or duration-Var(3) for a variable/custom interval set separately. An admin chooses this to control how frequently the associated performance variable is sampled and compared against the configured thresholds. As an illustrative example, an admin monitoring a fast-changing error counter might set this to duration-15m(1) for finer-grained alerting.