Sight Height
Also: Optical Centerline Height
The vertical distance from the bore's centerline to the scope's optical centerline. Critical input to any ballistic calculator.
Standard rings put the scope tube 1.5 to 2.0 inches above the bore on most precision rifles. Tall rings raise it more; very low rings get the optic close to the bore but with less cheek weld height.
Sight height affects the near-zero behavior of the bullet. Higher rings mean the bullet starts farther below the line of sight, climbs longer to the zero, and crosses LOS once more steeply. Plug the real number into your app; assuming 1.5 inches when you actually have 2.4 throws short-range dope off by inches.