This object is the low-water mark for this specific association's remote receive window. Tracking how low the peer's advertised window has gotten tells the admin whether that remote peer has ever been so backed up it nearly stopped accepting data from this device, useful when the peer itself does not expose its own receive-buffer metrics. A low mark of 0, combined with a nonzero zero-count on the companion counter, confirms the remote side fully stalled inbound acceptance at least once on this association.