This read-write integer reports and lets an external application set the STP state (blocking, listening, learning, or forwarding) of a port whose Spanning Tree processing is otherwise disabled, controlling what the port does with received frames. An admin cares because manually steering this state lets management software emulate STP-like frame handling on a port outside the normal protocol. For example, a management application could set this object to forwarding(5) on a port to let it pass traffic normally while automated logic elsewhere continues to track it as if under STP control.