Hey Miles,

Thanks for bringing this up. I love that small site!

However, including datetimes separated with either an underscore or a space as valid RFC 3339 is questionable at best. It all depends on a note in the RFC here: https://datatracker.ietf.org/doc/html/rfc3339#section-5.6. To me, that is not enough to consider it valid without a previous additional agreement.

The other differences to ISO8601 are trivial. So I still say RFC3339 is safe to use :)