Mostly, it's strict adherence to knowing who's turn it is to act offensively. Only moving forward when your training partner is in motion, or you have a strong position. Likewise, moving backward when you are weak, weakening. Chosing the correct actions to be done indes. Not going faster than necessary to be done indes. Understanding in a deep way what it means to be strong.
This is what we call in other martial arts, mostly karate-do styles, a study fight. It is not a contest or a free fight, in which your main goal is to gain a strike or point. Here the objective is to give way sort of speak. One would initiate an attack technique, the opponent responds and there might be a counter from the defender, and possibly a counter-counter again. This is a very difficult practice that requires a very high level of mastery, not something for beginners or intermediate students. There also must be a level of trust between each other. Knowing that the other person will not harm you. P. S. In savate there's a similar type of combat called combat de figure, basically a no-contact type of event.
