This is very neat, but maybe not completely accurate. "2021-10-24 11:02:03Z" is outside iso8601 in the figure, but I think it's valid iso8601. True, "T" is the One True date-time separator in iso8601 (IMO its biggest wart, as it looks awful for human eyes: "2021-10-24T11:02:03Z"). But according to the draft standard[1], page 21:
> By mutual agreement of the partners in information interchange, the character [T] may be omitted in applications where there is no risk of confusing a date and time of day representation with others defined in this International Standard
> By mutual agreement of the partners in information interchange, the character [T] may be omitted in applications where there is no risk of confusing a date and time of day representation with others defined in this International Standard
[1] The actual ISO standard is not freely available, but the Library of Congress has free draft standards: https://www.loc.gov/standards/datetime/iso-tc154-wg5_n0038_i... https://www.loc.gov/standards/datetime/iso-tc154-wg5_n0039_i...