This is another alternate routing metric slot for the entry, with its meaning defined by the routing protocol indicated in ipForwardProto, and set to -1 when not used. Like ipForwardMetric2 through ipForwardMetric4, admins would only see a meaningful value here for routing protocols that define a fifth distinct metric, otherwise it remains -1 for the vast majority of routes. For example, in a typical deployment using RIP or static routes, an admin querying this object would consistently see -1, confirming that metric dimension isn't used by those protocols.