... And I (a non-native English speaker living in the US) always have trouble remembering what 12 AM and 12 PM means, even after all these years I have to look it up every time, and sometimes it drives me nuts.
(For a moment I hoped your explanation would at least serve as a heuristics... but alas, it does not make sense to me. Well, at least at the moment I remember the notation).
Regardless of it, "12:00 AM of Jan 1, 2000" is not a particular second. It's a point in time, it has no duration.
It does not belong to any particular calendar hour or day or year, it's a _boundary_ between two.
Of course it belongs to XX century since XXI century starts at 12:00 AM of Jan 1, 2001.
The first second of Jan 1 lasts from 12:00::00 AM to 12:00:01 AM.
First minute of that day lasts from 12:00 AM to 12:01 AM.
Etc.
(For a moment I hoped your explanation would at least serve as a heuristics... but alas, it does not make sense to me. Well, at least at the moment I remember the notation).
Regardless of it, "12:00 AM of Jan 1, 2000" is not a particular second. It's a point in time, it has no duration.
It does not belong to any particular calendar hour or day or year, it's a _boundary_ between two.
Of course it belongs to XX century since XXI century starts at 12:00 AM of Jan 1, 2001.
The first second of Jan 1 lasts from 12:00::00 AM to 12:00:01 AM.
First minute of that day lasts from 12:00 AM to 12:01 AM. Etc.
At least this is how I parse it.