# ISO Datetime, minute precision (no timezone)

Key: `datetime.timestamp.iso_minutes`

ISO 8601-like format with minute precision (T separator) and no timezone indicator (e.g. 2013-06-04T01:02). The minute-precision sibling of iso\_seconds; common in exports that drop the seconds field.

Page: <https://meridian.online/docs/projects/finetype/types/datetime/timestamp/iso_minutes>

Format: `%Y-%m-%dT%H:%M`

Samples: `2013-06-04T01:02`, `2024-01-15T10:30`

## Background

### Origin

ISO 8601 writes a combined date and time as a complete date, the letter T as a delimiter, and a time.[[1]](https://en.wikipedia.org/wiki/ISO_8601) ISO 8601 allows the seconds, or the minutes and seconds, to be omitted from a time.[[1]](https://en.wikipedia.org/wiki/ISO_8601) Under ISO 8601, a time given with no UTC relation information is assumed to be in local time.[[1]](https://en.wikipedia.org/wiki/ISO_8601) The first edition of ISO 8601 was published as ISO 8601:1988 in June 1988.[[1]](https://en.wikipedia.org/wiki/ISO_8601) ISO 8601-1:2019, the fourth revision of the standard, was issued in February 2019.[[1]](https://en.wikipedia.org/wiki/ISO_8601)

RFC 3339, Date and Time on the Internet: Timestamps, was written by G. Klyne and C. Newman and published in July 2002.[[2]](https://www.rfc-editor.org/rfc/rfc3339) RFC 3339 describes its format as a conformant subset of the ISO 8601 extended format.[[2]](https://www.rfc-editor.org/rfc/rfc3339) RFC 3339's grammar makes the seconds field of a time mandatory.[[2]](https://www.rfc-editor.org/rfc/rfc3339) RFC 3339's grammar requires a time offset at the end of a date-time.[[2]](https://www.rfc-editor.org/rfc/rfc3339)

### Use

The HTML Standard defines a valid normalized local date and time string as a date, the letter T, and a time expressed as the shortest possible string for that time.[[3]](https://html.spec.whatwg.org/multipage/common-microsyntaxes.html) The HTML Standard's shortest form omits the seconds component entirely when a time is zero seconds past the minute.[[3]](https://html.spec.whatwg.org/multipage/common-microsyntaxes.html) MDN describes the value of a datetime-local input as a string representing a date and time in the local time zone.[[4]](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements/input/datetime-local) MDN notes that the datetime-local input provides no way to set the time zone of the control.[[4]](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements/input/datetime-local) MDN gives the datetime-local input a default step of 60, indicating 1 minute.[[4]](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements/input/datetime-local) A web form built on a datetime-local field is one plausible source of a column of values like 2024-01-15T10:30. (Meridian's view)

Python's datetime.isoformat method includes the hour and minute in HH:MM format when called with timespec='minutes'.[[5]](https://docs.python.org/3/library/datetime.html) Python's documentation shows isoformat(timespec='minutes') returning '2002-12-25T00:00'.[[5]](https://docs.python.org/3/library/datetime.html)

Treat these values as wall-clock times, and settle which time zone they belong to from the source's documentation before converting them to UTC. (Meridian's view) If a column mixes this form with values that carry seconds, check whether the minute-only rows are simply those that fell exactly on the minute before concluding the source dropped precision. (Meridian's view)

### Where you'll meet it

Open-Meteo's API documentation shows hourly time values written in the form 2022-07-01T00:00.[[6]](https://open-meteo.com/en/docs) Open-Meteo's documentation says the time zone offset is returned as utc\_offset\_seconds.[[6]](https://open-meteo.com/en/docs)

## Sources

1. [ISO 8601 - Wikipedia](https://en.wikipedia.org/wiki/ISO_8601) — secondary source
2. [RFC 3339: Date and Time on the Internet: Timestamps](https://www.rfc-editor.org/rfc/rfc3339) — standard
3. [HTML Standard](https://html.spec.whatwg.org/multipage/common-microsyntaxes.html) — standard
4. [\<input type="datetime-local"\> HTML attribute value - HTML \| MDN](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements/input/datetime-local) — secondary source
5. [datetime — Basic date and time types — Python 3.15.0 documentation](https://docs.python.org/3/library/datetime.html) — documentation
6. [🌦️ Docs \| Open-Meteo.com](https://open-meteo.com/en/docs) — organisation