The dressage phase (held first) consists of an exact sequence of movements ridden in an enclosed arena (20×60 m for International 3DE but usually 20×40 m for ODE). The test is judged by one or more judges, who are looking for balance, rhythm, suppleness, and most importantly, the cooperation between the horse and rider. The challenge is to demonstrate that a supremely fit horse, capable of completing the cross-country phase on time, also has the training to perform in a graceful, relaxed, and precise manner. Dressage work is the basis of all the other phases and disciplines within the sport of eventing because it develops the strength and balance that allow a horse to go cross-country and show jump competently.