This read-write CmPmIntervalType selects the fine-grained performance-monitoring bucket length, either 5 or 15 minutes, applied to all PM entities monitored at the Ethernet NTE GO102Pro-SM Card level, defaulting to 15 minutes. It matters because shortening the interval to 5 minutes on the Ethernet NTE GO102Pro-SM Card gives an administrator finer-grained visibility into short-lived error bursts that a 15-minute bucket, or the coarser 1-day/rollover counters, would smear out. For example, when troubleshooting intermittent errors on the Ethernet NTE GO102Pro-SM Card, an engineer sets this object to interval-5min to capture more granular PM statistics during the investigation window, then reverts it to interval-15min afterward.