Is there any calendar system that numbers days from zero? I'm sure that the Gregorian, Tamil, Chinese, and Discordian calendars don't. The closest thing I can t

Is there any calendar system that numbers days from zero? I'm sure that the Gregorian, Tamil, Chinese, and Discordian calendars don't. The closest thing I can think of is strftime's %w and %W flags for numbering days and weeks starting from zero.