"END" or "EN" stands for Endurance. It is one of the shows available on the English Register.
Endurance event includes the classes:
Endurance, 5 Miles
Endurance, 10 Miles
Endurance, 25 Miles
Endurance, 50 Miles
Endurance, 100 Miles
Although in real life no foal would be on an Endurance ride, on WOSE, Endurance can be a favorite, or excellent, event. WOSE foals ages 2-3 are capable of doing well in this class if they have excellent odds. If your horse has excellent odds in this event, it can go into any class and have excellent odds.