This counts outbound frames delivered on this circuit that carry the Discard-Eligible marking, showing the admin how much low-priority traffic -- possibly re-marked by the network itself during transit, or originally marked by the far end -- is being delivered toward this circuit's customer. For example, an unexpectedly high cktOutDEFrames count on a circuit whose customer never marks their own traffic as DE would suggest the network itself is re-marking frames as DE somewhere upstream due to congestion on this circuit's path.