1
Generally, events happen in a year, in a month, on a day and at a time. Whether you use the YYYY-MM-DD format recommended by ISO-8601 or some other format should not really have a bearing on the choice of preposition.
Here's a usage example, correct in my opinion, from the Wikipedia article on ISO-8601: 'An interval denoted "2007-11-13/15" can start at any ...
1
These numbers are pictograms that represent a date, so they are not words and they are not English. You can see this because you could write the date like this in any language. However when you read it you will have to read it in English. Perhaps you might say "on the twenty-first of May, 2019." But of course this will vary by dialect and personal preference....
Only top voted, non community-wiki answers of a minimum length are eligible
