39.9 When ordered to do so by the clerk of the course the observer in the car will use a green light to signal to any cars between it and the race leader that they should pass. These cars will continue at reduced speed and without overtaking until they reach the line of cars behind the safety car.
39.10 Except under Article 39.12 below, the safety car shall be used at least until the leader is behind it and all remaining cars are lined up behind him.
Once behind the safety car, the race leader must keep within ten car lengths of it (except under Article 39.13 below).
详见https://www.fia.com/sites/default/files/2021_formula_1_sporting_regulations_-_iss_7_-_2021-03-19.pdf