This read-only CmPmIntervalType specifies which PM interval (such as 15-minute or 1-day) is used when sampling the monitored E1/T1 variable and comparing it against its configured threshold. An admin needs to know this interval to correctly interpret how quickly a threshold-crossing alert can fire, since a 1-day interval threshold reacts far more slowly than a 15-minute one. If e1t1ThresholdInterval is set to 1-day for a circuit's LineCVs threshold, the admin knows an alert on that circuit won't fire until a full day's violations accumulate, and would choose a shorter interval if faster detection is needed.