The household Read in the Tamil Nadu reckoning, which is what decides the rule: the south counts a birthday by the birth star and the north and east by the birth tithi, and they are different days. Change the tradition on the calendar page and this follows it. The two dates a family keeps and a passport does not: the nakshatra birthday, the day the birth star runs again in the birth month, and the annual shraddha, on the tithi of the death. Both move against the English calendar, which is why they are worth a page. Everyone here is already on this device and goes nowhere else.