Meta.attr.date format

Help/How To
1

Does my example correct (I take it from media info)?
meta.attr.date.markup="UTC 2021-08-28 12:20:15"
Or day first? Year first or last? Instead of UTC what I can write?

2

It is Year-Month-Day. Instead of UTC, you can include a UTC offset.

Here is the definition of the date format that is used:

3

I have tried
meta.attr.date.markup="2021-08-28"
Why MediaInfo marks my field in big capital? Does “date” and “artist” non-standard for .webm ?
DATE

4

I do not know. It seems like that would be a question for whoever makes MediaInfo.