Less information needed to be imparted to the rock throwers ("rockers") since there was only so much you could say about rocks. They did actually need to be rocks, locally sourced. Some mischief-makers had tried to smuggle in eggs made of lead. You were not allowed to use slings or atlatl-like arm extenders. You had to throw the rock from your hand with a normal baseball- or cricket-like motion. As a way of driving the point home, the soldier took up a position about ten meters away from a sheet of plywood, very much the worse for wear, and used a sling to hurl a lead egg at it. The egg punched a neat hole right through the plywood. "Of course the rules apply on both sides of the Line," the lecturer said, "and that is where you, our intrepid streamers, have your role to play. Keep a sharp eye on our adversaries! If you collect any footage of Chinese volunteers transgressing these strict rules, upload it at once, timestamped and geotagged, to our server."