The best way to describe it is that the corners are cut off (to respect the geometric limits of the blade or its possible fuselage contact) by assuring that the corner will not be used in flight. The logoc is that if you need full forward cyclic and full up, you can't actually be flying.
Usually a clever stop or link is added to the controls system to provide the stop as a combination of the two controls, and this has to be part of the initial design. Often, you take both controls to a rotation bar where their bellcranks both independantly rotate and are side by side. This establishes a common point from which you can run a portion from one crank to the other that makes a mutual stop. That way, when one control is rotated beyond a certain point, it drags the other control along with it, which if properly designed, removes that other control input.