ISO 8601 provides readable, standardized strings for dates and times, improving API clarity and interoperability. It supports dates, date-times, UTC, and time-zone offsets. section 8.10 section 8.5.3
Readable transaction date
A bank transaction can use 1982-12-20T10:31:00Z instead of the opaque Unix timestamp 409228260. For date-only data, use 1982-12-20. The final Z identifies UTC; +01:00 can represent an equivalent local offset. section 8.5.3
Choose the representation according to the consumer’s needs:
- Prefer ISO 8601 strings when consumers need readable, clear, editable API values. section 8.5.3
- Use date-only precision when time is unnecessary; avoid extra precision that creates time-zone complexity. section 8.10
- Prefer UTC unless requirements call for an offset, and document timestamp units if numeric timestamps are used. section 8.5.3
