The heel of a point is the part opposite the switch tongue point (movable rail section determining the direction). Passing the point trailing or trailing the point therefore means taking the point from the opposite side to the tongue point. Some points are trailable (they can be crossed, regardless of the tongue point position), whereas others are not. This is the case for points controlled by notch-based levers (a safety notch locks the lever), which is likely to be damaged by forcing open the points.