The third mode for telehandler steering is known as crab steer since the machine moves sideways In fact it moves diagonally. Again the trainees should be allowed to practice left and right steer, forwards and backwards. This mode can take a bit of getting used to as it seems unnatural at first.
In fact crab steer mode is rarely used in practice but it can be useful for moving the machine a little sideways in order to line up with a stacking position in much the same way as a sideshift does on a conventional forklift truck. For this reason I don't believe it should be used during a test.