Rich is right, since this is the date format that sorts correctly in filenames.

Alt text:

ISO 8601 was published on 06/05/88 and most recently amended on 12/01/04.

I am a big fan of iso 8601, I just wish it was possible to write more dates than February 27th, 2013 with it

There are several people in the comments saying they have to use 27 Feb 2013 because they work with people all over the world. I’m really confused - what does that solve that 2013-02-13 does not? I know that not every language spells months the English way so “Dec” or “May” aren’t universal. Is there some country that regularly puts year day month that would break using ISO 8601 or RFC 3339?

I propose that we amend the ISO to require the days of the week be named after their etymological roots in that language.

English Days of the Week:
Day of the Sun
Day of the Moon
Day of Týr
Day of Odin
Day of Thor
Day of Frēa
Day of Saturn

Imagine dating a meeting, "Day of Odin, May 7, 2025." Imagine a store receipt that says, "Day of Thor, June 5, 2025." Imagine telling a friend, "July 4th falls on a Day of Frēa this year!"

THIS IS WHAT WE COULD HAVE. THIS IS WHAT WE HAVE LOST. THIS IS WHAT WAS STOLEN FROM US.

We could bring it back. We could make this the norm. We could make this real. We could summon this bit of ancient magic back into our world. Let's remember what we actually named these days for! BRING BACK THE DAY OF THOR!

My goodness, some of the comments in here must come from people who thought that those writing the standard were morons who did no research.

The sane way of dealing with it is to use UTC everywhere internally and push local time and local formatting up to the user facing bits. And if you move time around as a string (e.g. JSON) then use ISO 8601 since most languages have time / cron APIs that can process it. Often doesn't happen that way though...

Is that the same guy who wrote Standards? tsk, tsk.

Where I live, "DD. MM. YYYY" is the standard but some old tombstones use

2013-02-27 is a weird way of writing 1361923200

ISO 8601 allows all kinds of crazy time stamps. RFC 3339 is much nicer and simpler, and the sweet spot is at the intersection of ISO 8601 and RFC 3339.

Then again, ISO 8601 contains some nice things that RFC 3339 does not, like ranges and durations, recurrences...

https://ijmacd.github.io/rfc3339-iso8601/

RFC-3336

I figured there were problems with existing calendars, so I created a new one to supersede all others. That reminds me, though: I need to declare the "official" format for the calendar, to avoid all this nonsense.

I see a window of opportunity, here. Normally, there's no chance for any calendar revision to succeed in adoption; however, I think if I use the right words with the President, I could get it pushed into adoption by fiat. Y'all had best start learning my new calendar to get ahead of everyone else.

Note for the humorously disadvantaged: the Saturnalia Calendar is a mechanism through which I'm playing with a new (to me) programming language. I am under no disillusion that anyone else will see the obvious advantages and clear superiority of the Saturnalia Calendar, much less adopt it. And no comments from the peanut gallery about the name! What, did you expect me to actually spend time thinking of a catchy name when a perfectly good, mostly unused one already existed?

It's the only way.

Issue: there are 27 different ways of writing a date.

Engineers: We most make a common standard that is unambiguous, easy to understand and can replace all of these.

Issue: there are 28 different ways of writing a date.

Joke aside, I really think the iso standard for dates is the superior one!

2013-02-27 = 1984

I regularly work with Americans, Canadians, and Europeans. So many times each group defaults to their own format and mistakes occur I gave up on all the formats listed by OP. If i have to write a date in correspondence its like: Feb 27th 2013. No ambiguity. No one has ever challenged me on it either. It is universally understood.

I feel like YYYYMMDD (without dashes) might be a format in ISO 8601, but I'm fully expecting to be corrected soon. But I didn't say think, I said feel. YYYYMMDD has a similar vibe to YYYY-MM-DD, ya feel me?