Eventing is an equestrian event which comprises dressage, cross-country and show jumping, also called stadium jumping. This event has its roots in a comprehensive cavalry test requiring mastery of several types of riding. It has three main formats: the one-day event (ODE), two-day event and the three-day event (3DE), which in reality now runs four days at some competitions. The sport was once referred to as "Militaire", and there is also a format in which riders complete all three events in one day, called a "horse trial". Also, a "combined test" is a variation of eventing which encompasses any two of the phases, most commonly dressage and show jumping, but will sometimes be cross-country and show jumping or cross-country and dressage.