Reply to Traktor x1 hotcue midi button question

Hi there, Tomorrow my x1 will arrive home, so, today, I started writing down the mapping (on paper).
After I figured out what I really need in the mapping I was believeing about the billion of modificators, and a big question, what do "hotcue" button really do? Is a simple midi button that in standard mapping is assign to a modificator? Or it changes the note of the 16 buttons?