The extended format separates fields with hyphens and colons. The basic format omits them.
Date and time
Calendar date2026-03-14
Ordinal date2026-073
Week date2026-W11-6
Time09:41:07
Fractional seconds09:41:07.250
Combined2026-03-14T09:41:07
Offsets
UTC designator2026-03-14T09:41:07Z
Positive offset2026-03-14T11:41:07+02:00
Negative offset2026-03-14T04:41:07−05:00
Basic offset20260314T094107+0000
Durations and intervals
DurationP3Y6M4DT12H30M5S
WeeksP8W
Interval2026-01-01/2026-12-31
RepeatingR5/2026-01-01/P1M
Ordering fields from most to least significant makes lexical sorting equal to chronological sorting.