This read-only counter, in cells, tracks the number of valid ATM cells with the EFCI header bit set to 1 in the egress direction of this channel, measured before the class-of-service queue, meaning these cells were already marked as having experienced forward congestion. An admin monitors this to see how much outbound traffic on this channel is already flagged as congested by the time it reaches the switch's egress class-of-service queue, informing the downstream network of conditions upstream. For example, a rising count here tells the admin that congestion is being propagated forward toward the destination for this connection, which the receiving end can use to adapt its own behavior.