Startup Box - Holladay axial length

What is the Holladay axial length adjustment box? I have used Wang-Koch in the past, and see no documentation about what that is? I know Wang-Koch requires using the Holladay 1 equation.

Please click on the AXIAL LENGTH ADJUSTMENT BUTTON on the MAIN MENU and it is fully explained. In short, it is better than the Wang Koch and avoids myopic as well as hyperopic errors in long eyes. It specifically adjusts for both the Holladay 1 and 2. It is also important in toric calcs for the same reason.