This read-only counter, in cells, tracks the number of valid CLP=0 cells in the ingress direction of this channel that the UPC (traffic policing) function re-tagged as low priority rather than outright discarding. An admin cares because this shows the policing function is using a softer enforcement action, downgrading priority, rather than dropping cells outright, which can still lead to later loss if downstream queues become congested. For example, if this tagged count is rising, the admin knows some of the connection's supposedly high-priority traffic is now competing as low priority further downstream, and might correlate this with subsequent CoS discard counters to see if it ultimately gets dropped.