Deli and Luka you are both right, the red ribbon means the horse kicks and you better not get too close!
I wish every rider would know what it means and respect it!
I had a bad experience in one of my first shows as a teen riding my favorite horse who was a kicker and a girl passed me so close on the inside that our knees and stirrup irons bumped together. Sure enough my horses ears pinned back and she was ready to kick the other horse when I used my inside rein to correct her and she bucked me off! We had to stop the class and I got back on and finished but didn't win anything. My riding teacher said I did the right thing so she didn't kick the other horse but I think I should have just let her kick her.

I think Equine is right, or is it Square Off or Stand Square?