Horse leg markings are a varied as the animals that display them.
Almost all horses have leg markings of some sort, from a tiny spot of white to whole white legs. Here are the general definitions of each marking (which are a bit more definitive than markings on the face because they are based on leg anatomy.
This is the smallest of the leg markings & shows the least amount of white. The mark is only displayed around the coronet band, generally rising no more than in inch up from the hoof.
Often difficult to distinguish from the coronet marking, the pastern takes up where it leaves off. The white mark extends more than an inch above the hoof over the pastern but stops at or below the fetlock joint.