This object identifies which CoS mapping table entry this static transit tunnel uses, valid only when its frame CoS policy is set to the mapped option, as the description states. This lets a mid-path router apply its own, potentially different, CoS translation to transiting traffic than whatever mapping was applied at the ingress point, which matters if different routers along the path maintain independent CoS mapping tables. For example, a map ID of 8 referenced at this transit hop could translate incoming priority markings differently than the map ID referenced back at the tunnel's ingress point.