For a correct rein back, Ms. Later explains that you must first have a correct halt. She describes and demonstrates how the horse must do this with a soft back and no increase in the rein pressure. She then explains the aids for the rein back and gives instruction on what to do when things go awry. There is also a description of how to begin the training of the rein back.
For the more advanced horses, Ms. Later takes us through the trot halt rein back transitions. She discusses how the rein back is a great exercise to check on the connection from the rein to the hind legs, and how a problem with the rein back can show problems elsewhere in the ride. She stresses it should never be used as a punishment.