What is the meaning of "throw a caution flag" in this:
"He was leading with seven laps remaining when NASCAR threw a caution flag for a crash between Jeff Gordon and Clint Bowyer, setting up a green-white-checkered restart. "
I understand that for sports car racing, if there is some problems on the race track, someone would go out and show/fly/wave a yellow color flag (caution flag). But does 'throw a caution flag' also mean 'show/fly/wave a caution flag', or does it mean something else?
context info from: aol.sportingnews.com/nascar/story/2012-11-11/nascar-phoenix-results-2012-drivers-upset-no-caution-flag-last-lap-wreck-danica-
It seems to mean the same as: show, display, fly, or wave.