For APIs, logs and files, include the time zone or UTC offset when the moment matters. A local time without zone information can be ambiguous.
| Kind | Example | Meaning |
|---|---|---|
| Calendar date | 2026-08-31 | Unambiguous date |
| UTC timestamp | 2026-08-31T01:23:45Z | Z = UTC |
| Offset timestamp | 2026-08-31T10:23:45+09:00 | Local time plus UTC offset |
| Month | 2026-08 | Reduced precision |
| Week date | 2026-W36-1 | ISO week-based date |
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Sources & update policy
Verified: 2026-08-31. This page prioritizes primary standards and official registries. Time-sensitive items should be rechecked against the linked source.