Do you know why an “oxer” is called an “oxer”?
The name came from the practice of putting parallel rails on either side of a hedge to keep oxen from damaging natural hedges.
In the early day of foxhunting, riders jumped these hedges and rails as they followed the hounds, and those obstacles became known as oxers.
An authentic example of an oxer is still seen at Hickstead in England. Modern-day oxers can be any kind of jump with parallel rails, but the back element can only have one rail.