1) Oblique lines 2) Virgules or twills 1) Slantedlines 
Right front and left rear legs constitute the right diagonal; left front and right rear legs constitute the left diagonal. In the trot, the diagonals move together.
Right front and left rear legs constitute the right diagonal; left front and right rear legs constitute the left diagonal. In the trot, the diagonals move together.
The horse's legs move in pairs at the trot, called diagonals. The left diagonal is when the left foreleg and right hindleg move together, the right diagonal is when the right foreleg and the left hindleg move together.