Discussion on answer by tchrist: Why is 11 am + 1 hour == 12:00 pm?

I wonder where he saw "12:00 p.m." written.

I would say that noon is an infinite small instant at the very moment between 11:59:59.999999~ and 12:00:00.000000~, but clearly the "time guys" at the NIST don't agree. I don't think that the question "what is the duration of noon?" can be easily answered.

I was one day early to a "midnight release" event because I understood midnight to be the very start of that day, but the even was actually at the end of the day. I now see many "midnight release" events with a time of 11:59PM to avoid confusion and it makes me happy when I see that.