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These problems can be very difficult to solve if you want to show a different format for your users.
If you want a world-readable unambiguous date/time system, look to International Standard ISO 8601, which answered this question in 1971. Less than half a dozen countries have not signed up to this standard.
You could just default to using that, or else provide a menu option for people to choose their display format, with the default as the ISO standard.
I think it's quite obvious. It goes from largest to smallest (year.month.day). I've never seen the date format: year.day.month.