This Counter64 measures bytes transmitted out of the lower interface of the Transport layer, specifically the data volume after compression has been applied plus the Transport header overhead. Comparing this raw wire-level figure against cnt2TransportOutOctets lets an admin estimate how much the compression stage is shrinking the payload before it hits the link. For example, if RawOutOctets is consistently much smaller than the uncompressed application data volume, the transport's compression is doing significant work.