This read-write object holds a third alternate routing metric for a route entry, with its meaning again defined by the route's clnpRouteProto value and -1 indicating it is not used. An admin encountering a nonzero value here would consult the specific routing protocol's documentation to understand what this particular metric slot represents for that protocol. For example, a routing protocol that reports up to five distinct metrics per route, such as delay, expense, and error, could use this slot for one of those additional figures beyond the primary and secondary metrics.