Back to the original meaning of the post. Back in the 70s some tracks qualified and started the fast guys on the tail Full inversion fields. To keep drivers from sandbagging their qualifying for a better starting possition, there was a one second rule. If you beat your qualifying time by a second or more. You were disqualified for the night.

I think Butch Wilkerson could shed some light if he wants too. From what I understand it was basically done by stopwatch if they thought someone was running faster than they qualified.