(14)...d. ...school trot actually results from transitions between lively extended and lively shortened phases of the regular trot, both in horizontal balance...
(14)...e. ...in the process of thus developing the school trot the rider must pay attention to the diligence, rhythm and fluidity of the horse's locomotion...
(14)...f. ...all too easily the horse, with tightened back muscles, comes up with those slow, floating steps, which are wrong because legs are dragging and the horse misses proper impulsion...
(14)... details on causes...
(14)...g. ...the required activation of the horse's hind legs must thus be administered with light and lively touches of the rider's legs. They adventageously can be supported with a tactful use of the long whip...
(14)...h. ...likewise the rider's hand must allow room to permit the horse's steps. The rider should seek to support collection not with a steady hand, but with repeated soft movements of his ring fingers, which guard and maintain the suppleness of the horse's jaw (...Arrets...)...