Code.
I believe in the bdsm world the color code is a standard that should be teach for the start.
The only code that any one should know is at least the RED. The point is to make sure we got a word or code to say its over game finish.
Last night I was at l’espace a local fetish event, and a girl was calling red 2 times and his master was continuing to play, so I yell “Yay she say RED,” in case he didn’t hear it. For them a red was like a yellow or go smoother but not a stop.
We use different code to put a level on pleasure, pain or energy, but is very important to know the meaning behind some of the code.