... between the Saxonia AC and the Langematik PC: When you push the corrector button at the 10 o'clock position on the PC, every function (day/date/moonphase) advances by 1 full day. Because of this, you literally never have to reset any of the individual calendar functions if you stop wearing the watch for a while. You just push that one button once for each day that passed since the watch stopped. When you push that same corrector button on the AC, only the date advances.