Eventing combines three equestrian disciplines: dressage, cross-country and stadium jumping. The sport's roots are in the cavalry, where strength, stamina and communication were necessary to see a horse and rider through battle; eventing was introduced at the 1912 Olympics in Stockholm as "The Militaire." Originally, only active-duty Army officers and their mounts competed, but the sport was opened to civilians in 1924. Female riders were not allowed until 1964.
How it's scored
Scoring is based on penalties, with points added for each mistake. The horse and rider combination with the lowest score after completing all three phases wins.
What to watch
Dressage: Each horse-and-rider pair completes the same intricate test pattern in a 20-by-60-meter (about 65 feet by 197 feet) arena. Riders are awarded points (up to 10 for each movement) based on how well they complete the maneuver and how well they transition from one gait, such as a trot or canter, to another.
Cross-country: This phase tests a horse's athleticism and stamina, with up to 40 jumping efforts along about a 6,300-meter (about 3.9 miles) course in an optimum time of about 11 minutes.
Obstacles can be up to 3 feet, 11 inches high, with brush fences up to 4 feet, 9 inches.
Riders have a choice of route over the trickiest jumps: shorter but harder, or longer but easier. Different types of jumps present various challenges: skinny fences test a horse's accuracy; corners, which can prompt a horse to run out to avoid a jump, test discipline.
The first refusal adds 20 penalty points; the second adds 40. A third refusal means elimination. A fall on the course, even if both horse and rider are uninjured, results in elimination.
Stadium jumping: The last phase of competition requires a horse to come back after an arduous cross-country day with an effort to clear up to 16 jumps, some in combinations of multiple jumps per fence. Maximum height of jumps is 4 feet, 1 inch.
Dressage: Spectators should remain quiet until the rider has completed the test.
Cross-country: Cheering is acceptable when the horse and rider are in open areas, but spectators at jumps should be quiet until the horse and rider have completed the jump or series of jumps.
Stadium jumping: Spectators should wait until the end of the rider's round to cheer.
■ Dressage riders usually wear a double-breasted, long-tailed cutaway coat called a "shadbelly." Riders in red have represented their country in international competition. Riders in the military wear uniforms. Riders rarely wear helmets while competing in dressage, but a growing movement in the sport has advocated helmets rather than top hats for safety.
■ Cross-country riders walk the course beforehand, but horses see it for the first time during competition.
■ Stadium jumping pairs are not judged on style, but timing does count. Exceeding the time allowed adds penalty points.
■ Eventing horses must pass two veterinary checks — before the competition starts and before stadium jumping. Horses also are examined by a vet after the cross-country competition.
Countries competing (based on preliminary nominations): 15 countries have eventing teams; six countries will be represented by individuals.
Individuals competing: 98 athletes have been nominated to compete in eventing.
Awards: Medals and trophies will be presented to winning countries and individuals.
JANET PATTON, firstname.lastname@example.org
Dressage, part 1, 9 a.m.
Dressage, part 2, 1:30 p.m.
Dressage, part 3, 8:30 a.m.
Dressage, part 4, 1 p.m.
Cross-country, 9 a.m.
Stadium jumping, 1 p.m.