The FIA has tightened up its restrictions on Formula 1 radio communication ahead of this weekend's Hungarian Grand Prix.
The move follows Nico Rosberg's incident during the British Grand Prix when the Mercedes driver informed his team of a gearbox problem, and was then instructed on how to correct it.
After finishing second to team-mate Lewis Hamilton, Rosberg received a 10-second time penalty that demoted him to third behind Red Bull's Max Verstappen.
Mercedes opted against appealing the penalty.
In a technical directive issued to F1 teams on Wednesday, the FIA has now significantly altered item number two on the list of permitted messages.
It previously read: "Indication of a critical problem with the car. Any message of this sort may only be used if failure of a component or system is imminent and potentially terminal."
It now reads: "Indication of a problem with the car. Any message of this sort must include an irreversible instruction to enter the pits to rectify the problem or to retire the car."
If the ruling had been in place at Silverstone, Rosberg would have been required to return to the pits where the team would have been allowed to inform him how to correct the gearbox issue he was experiencing.
Item number three of permitted messages, relating to "information concerning damage to the car" has also been tweaked, and now states: "Information concerning damage to the bodywork of the car."
There is also an addendum to message four, which now reads: "Instructions to select driver defaults. This must be for the sole purpose of mitigating loss of function of a sensor, actuator or controller whose degradation or failure was not detected and handled by the on-board software."
The messages now refer to all times the car is out of the pitlane, rather than garage as was previously the case, with the wording "with the exception of any time the car is in the pitlane on the day of the race prior to or between reconnaissance laps".
Now it is with the exception of "the slowing down lap once the driver has crossed the line at the end of the race".