a. either a protective structure to ensure that the equipment does not tilt more than a quarter turn, or b. a structure that ensures that there is sufficient clearance around the operator or ride-on employee should the tilting movement continue beyond a quarter turn, or c. another device of equivalent effect.
a. a structure that prevents it from rolling over, or b. a roll-over protective structure, or c. a structure that ensures that there is sufficient clearance between the ground and the equipment should the lift or stacker roll over, or d. a structure restraining employees in the driving seat and thus prevents them from being crushed between the ground and parts of the lift or stacker should it roll over.