Formula One has clarified the rules on radio communication between teams and drivers in the wake of incidents that have cost competitors points this season.
The clarification from the International Automobile Federation (FIA), the sport's governing body, makes clear that a team can inform a driver of a problem with his car but must order him to enter the pits for a decision on what to do.
The technical directive, from Formula One race director Charlie Whiting ahead of Sunday's Hungarian Grand Prix, defines more clearly what teams can tell drivers during a race.
The document says "any message of this sort must include an irreversible instruction to enter the pits to rectify the problem or to retire the car".
The FIA has acted following some high-profile incidents relating to instructions from teams to drivers on the track.
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At the British GP on July 10, Mercedes' Nico Rosberg was found to be in breach of the rules restricting what information could be conveyed.
The German, nursing a potentially terminal gearbox problem, was hit with a 10-second time penalty that demoted him from second to third after the team gave him instructions on how to get around it.
At the time, Mercedes, which decided not to challenge Rosberg's penalty, argued the messages were legal as the rules permitted communication regarding a terminal problem.
Force India's Sergio Perez crashed out on the last lap of the Austrian GP a week earlier with brake problems after the team felt the rules prevented them informing the Mexican of the issue.
Following the clarification, teams will be forced to bring a driver into the pits if they inform him of a critical problem where they will then be free to help him fix it or retire the car.
Coming into the pits will, however, cost the driver a significant chunk of time.
The fresh directive also clarifies that the radio restrictions will not apply if a car is in the pit lane, whereas earlier they kicked in as soon as the car left the garage.
