4 ms·

There's this handy venn diagram that I've seen floating around for a long time. Just found a random link to it with an image search: https://gyazo.com/d8517f7

• badmintonbaseba 1y ago
  That's a screenshot of this website: https://ijmacd.github.io/rfc3339-iso8601/ https://ijmacd.github.io/rfc3339-iso8601/
  • jcul 1y ago
    Thanks! That's where I remember it from.
• skissane 1y ago
  > ISO 8601 does have some strange formats... Not that I’ve ever really had cause to use it in anger, but I like the idea of ISO week dates. Effectively, the ISO weak year (often differs from the calendar year in the last week of December / first week of January), ISO week number and day of week form a leap week calendar - instead of having 365 days in a common year and 366 in a leap year, it has 364 days in a common year and 371 in a leap week year, with leap weeks (obviously) being less frequent than leap days. The Sym454 calendar [0] takes this idea further to create a perpetual calendar, with 12 months of 4 or 5 weeks; in leap years the 12th month is 5 weeks instead of 4 weeks long. However, the leap week rule proposed by Sym454 is different from that proposed by ISO 8601; the author of Sym454 argues his proposed rule has theoretical advantages (simple calculation and more uniform distribution of leap weeks). That said, there is a variant of Sym454 which uses the ISO 8601 leap week rule. [0] https://kalendis.free.nf/symmetry.htm?i=1 https://kalendis.free.nf/symmetry.htm?i=1