csDs3Ds1CurrentDMs is a read-only PerfCurrentCount counter reporting the number of Degraded Minutes — a one-minute period, excluding severely errored seconds, whose error rate exceeds one error per million bits — that this channelized DS1 (T1) circuit carried inside the DS3 has recorded in the current 15-minute measurement interval, i.e. right now. A rising count here is the operational signal that a DS1 that stays up but runs with elevated background errors is happening on that interface, which is exactly the kind of degradation a monitoring admin wants an early warning of before it causes an outage. For example, an admin polling csDs3Ds1CurrentDMs on this channelized DS1 (T1) circuit carried inside the DS3 every few seconds and watching the count jump upward in real time would immediately suspect a DS1 that stays up but runs with elevated background errors, and could start a bit-error-rate test before the fault gets worse.