I believe it enables you to choose regular or Potsmasher wash. If it were TOL, it might even have the option of the shortened, no-heat China & Crystal cycle. The Potsmasher extends the wash into the first rinse to give about 7 or 8 extra minutes of washing. Seems funny that Hotpoint would not have cycle pushbuttons since they were the pushbutton kings in the 50s, but Hotpoint had the little dial under the timer to choose the cycles while GE had the buttons.
I almost think that little dark emblem under the unicouple is the stylized Hotpoint H.