The procedure was used in NASCAR racing series when the pace car was deployed as a result of an on-track emergency such as a crash or rain. When NASCAR declared a caution period, racing would not cease immediately; rather, the drivers could continue racing for position until they crossed the start-finish line and received the caution flag. Passes for position counted, and drivers running a lap down (or more) were able to un-lap themselves if they passed the leader prior to the start/finish line.