State the date format explicitly

[sean-hut]

Problem

The ISO 8601 date format is ambiguous for 132 of the days of each year (about a third).

For example 2019-02-10 which is it YYYY-MM-DD or YYYY-DD-MM. The changelog does not say.

Proposed Solution

Explicitly state the date format.

Example

This commit is an example solution.

[jeffpaul]

@sean-hut I'm not aware of places where YYYY-DD-MM is utilized. Where have you seen that in use that would cause this potential confusion? Also, this seems like something for the Confusing Dates section and not where you're proposing this change.

[sean-hut]

I'm not aware of places where YYYY-DD-MM is utilized. Where have you
seen that in use that would cause this potential confusion?

What I am suggesting is that there will be people out there that when
presented with a date like 2030-03-10 will not know if it is
YYYY-MM-DD or YYYY-DD-MM.

Situation:

• a project is using the keep a changelog format
• a user of that project is reading the changelog
• the user is not knowledgeable in the variety of date formats
• there are ambiguous dates in the changelog

Outcomes:

• if there is no link to https://keepachangelog.com
  • they guess
• if there is a link to https://keepachangelog.com
  • follow the link
    • guess after giving up before reading far enough down the page
    • find the date information after reading far enough down the page
  • don't follow the link
    • they guess

this seems like something for the Confusing Dates section and not
where you're proposing this change.

It is because of the situation and outcomes described above that I
suggested the date format be explicitly stated in the actual
changelog. This would removing the ambiguity of the date format.
It also eliminates the hunting for the date format described above.

[Nixinova]

there will be people out there that when
presented with a date like 2030-03-10 will not know if it is YYYY-MM-DD or YYYY-DD-MM

Are there? Really? I can't think of a single reason why you would use YYDDMM let alone assume an an unambiguous ISO date would be in that format.

[NicoHood]

@Nixinova I agree with sean, as I am always confused. I've seen so many projects and changelogs. They do it all different (which is okay), but having this very short, but super helpful information is really great! I am wondering, why I wasnt using this before, thanks @sean-hut

[koppor]

Explanation: https://www.explainxkcd.com/wiki/index.php/1179:_ISO_8601

[jeffpaul]

@olivierlacan sufficient to close this as invalid as ISO standard is clear the format is YYYY-MM-DD.

[koppor]

I personally really like a hint to the date format. Nevertheless, I would refine the PR

My proposals would be:

• Craft a new version 1.2.0 containing a hint to the date format in the "Frequently Asked Questions".
• Put the note to Added for the Unreleased version in CHANGELOG.md.

[phieri]

There is a typo: changlog instead of changelog.

[jeffpaul]

@sean-hut ^

[koppor]

I personally learned more. The RFC 3339 defines a profile for ISO 8601.

I would propose:

This changelog uses the `full-date` format of [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339#section-5.6), which is `YYYY-MM-DD`.

[ravage84]

@koppor while your proposal would be technically more precise, I feel it's an overkill due to unnecessary complexity.

Just open your referenced link. Does one really need to know all these semantics to understand that a date (a "full date" that is) is represented as simple as YYYY-MM-DD?

[ravage84]

Shorter version (no need to mention "the changelog" & highlight the format:

Suggested change

	This changlog uses the [ISO 8601 date format](https://www.iso.org/iso-8601-date-and-time-format.html) of (YYYY-MM-DD).
	Dates use the [ISO 8601 date format](https://www.iso.org/iso-8601-date-and-time-format.html) of `YYYY-MM-DD`.

[ravage84]

Agree with @koppor , it should get a change log entry.

Suggested change

	### Added
	- Mention use of [ISO 8601 date format](https://www.iso.org/iso-8601-date-and-time-format.html) (`YYYY-MM-DD`).