I agree with and independently also use the parent's modification to ISO8601 with that respect; though I do frequently call the format string that contains what

I agree with and independently also use the parent's modification to ISO8601 with that respect; though I do frequently call the format string that contains whatever magic cookies get that output something similar to iso8601mod. (The modifications: Emit a string rather than a T, and (if included) use the email like +/-OFFSET to indicate the current timezone offset rather than specify a timezone. No offset implies UTC for system times and local time for human-facing times.)