With the goal of ensuring optimum tooth flank contact, the teeth of gear pairs can undergo flank corrections based on three different approaches according to the standard (ISO 21771:2007, September 2007), i.e. Flank line crowning, Flank line slope modification and Flank line end relief. By pressing on ‘Tooth flank modifications’ at the page ‘Gear connections’ a pop-up window allows the user to enter the corresponding geometrical data in relation with these approaches. For each gear it is possible to have either symmetric or unsymmetrical modifications by setting or clearing the available flags respectively at the bottom. By activation of an unsymmetrical flank modification, the corresponding data column is added in the window.