Aw - I wouldn't mind personally going the full nine yards for metric time, as I've already adopted the YY-MM-DD and the 24h time notation:

"This property also makes it straightforward to represent a timestamp as a fractional day, so that 2020-12-29.54321 can be interpreted as five decimal hours and 43 decimal minutes and 21 decimal seconds after the start of that day, or a fraction of 0.54321 ("54.321%) through that day (which is shortly after traditional 13:00). It also adjusts well to digital time representation using epochs, in that the internal time representation can be used directly both for computation and for user-facing display.

https://en.wikipedia.org/wiki/Decimal_time:

Written 2020-12-29.87500 Metric UTC

-Decimal year, month and/ or date - Anyone?

-Come out, all ye secret users of https://en.wikipedia.org/wiki/Swatch_Internet_Time

-Heck, we all know that 9 p m is exactly 87.5% of a day!

Cheers

Johan (non OFF)