Updated date/time definitions

[roll]

• fixes Time formats should be more consistent and portable across platforms specs#487

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Rationale

This pull request is based on comments in frictionlessdata/specs#487 and tries to apply the least invasive and non-breaking changes. It extends default datetime formatting although it keeps simple date and time.

It might be too late to remove pattern and any formats because of backward-compatibility requirements but what if we add a note that it's RECOMMENDED always use default formats (or even using SHOULD)?

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[roll]

Thanks @peterdesmet! It's been updated based on your comments!

@khusmann
@ezwelty
@pwalsh
@PietrH
@nichtich
Can you please take a look -- this change is also a good candidate to be accepted. Currently, it misses only 2 votes

[ezwelty]

If any cannot be removed, I would add a SHOULD (not), because its use can lead to ambiguous data, which is exactly the situation a metadata spec is supposed to fix.

pattern complicates automatic parsing of the data by software tools, but at least it serves the purpose of recording an explicit format, so I would only add a (not) RECOMMENDED. To me this falls in the same category as numeric groupChar in allowing vernacular (if not globally / computationally default) formats.

[roll]

@ezwelty
I would suggest adding NOT RECOMMENDED to any format on this iteration and we can increase the strictness on next iterations. Personally, I'm favour of complete removal of any non fully interoperable parts of the spec but I think that doing so step-by-step is more realistic.

[roll]

Thanks!

ACCEPTED by WG (7/9)