A vertical constraint controls the Y distance between two points on one object, or between two objects.
linear dimension represents the distance between two points, a vertical constraint parameter defines and controls the vertical distance between two points.
While aIn the example below, the polygon on the left has a vertical constraint of 2 units applied to the left line of the polygon. When that polygon is rotated counterclockwise, the result is the polygon on the right. The constrained points will remain 2 units apart vertically.