This read-write TruthValue object marks the connection's associated preferred route as a directed route, meaning it is the only permitted path for the connection, which fails if that route becomes unavailable; it has no effect without an associated preferred route. An administrator enables this when a Frame Relay circuit must never silently fail over to an alternate path. For example, a PVC subject to a contractual guarantee about its exact network path would have this object set to true so any deviation results in a visible connection failure rather than a silent reroute.