Wave-by

A wave-by is the procedure that lets cars caught out of position under a safety car recover their lap: cars sitting between the safety car and the leaders are released to drive past the queue and rejoin at the tail, restoring them to the lead lap or to their rightful gap.

In multi-class racing the mechanism matters double, because a safety car freezes four separate races at once and traps different classes in different queues. The wave-by is how race control untangles that knot before green; without it, a GT crew's race could be decided by which safety car happened to pick them up.