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Comment by bpicolo | Hacker News Reader

It’s not unambiguous. 2023-01-02 is as ambiguous as 01/02/2023 unless you’re a tech persona with precursor knowledge of date formats.

Edit: Good point, bashinator <3

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I think it's definitely less ambiguous because there are no locales (that I know of) that use YYYY-DD-MM, whereas MM-DD-YYYY and DD-MM-YYYY are both quite common. So, with a little bit of experience, if you ever see four digits first you can be 99% sure that the next part of the date is the month.

Edit: I also think that you don't need to be involved in tech in any way to be aware of date formats. They show up in all kinds of everyday places like tax documents, bills, cheques, receipts, exams, etc.

For contexts where you want humans to understand and don't need lexical sorting (paper documents definitely fall into this category), you can make it super unambiguous – July 15, 2023. Can't mess it up.

Challenge accepted!

October 15, 2023... octo... that must be... the 8th month!

??/??/YYYY is ambiguous because ~3 billion people use DD/MM/YYYY whereas the US uses MM/DD/YYYY. Nobody (or very few) uses YYYY-DD-MM, so YYYY-MM-DD won't be confused with it.

Could say that there's still a small amount of ambiguity, but it's definitely not "as ambiguous as" ??/??/YYYY.

> unless you’re a tech persona with precursor knowledge of date formats

YYYY-MM-DD is the standard for billions of people. You don't need to be a tech persona to either use it or to understand the reasons for it (lack of ambiguity, consistency with other numbers).

Using duodecimal for the month will clear that remaining confusion right up, YYYY-M-DD.

Unicode has you covered!

https://en.wikipedia.org/wiki/Duodecimal

So M is one of {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ↊, ↋}.

  U+218A ↊ TURNED DIGIT TWO
  U+218B ↋ TURNED DIGIT THREE

There are other contenders for the 11th and 12th symbol, but all of those systems seem to assume counting from 0, which is... not a very fortunate choice: Human calendars generally numerate the first month as "1", not "0". So duodecimal does not get my vote for less ambiguity on either the account of determining what symbols to use, or where to start the sequence. :-)

Bad example; 01/01 is unambiguously Jan 1 no matter how you read it.

@bashinator

Sure :)

But to their credit, @bpicolo makes a very valid point.

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