If you are talking about the instant, that kind of makes sense. However, there is also a period of time, written as 12:00 PM, which lasts for one minute, until

If you are talking about the instant, that kind of makes sense. However, there is also a period of time, written as 12:00 PM, which lasts for one minute, until 12:01 PM. This period of time is entirely within the afternoon, so writing it as 12:00 PM makes plenty of sense. This period of time is not "noon", although that is when the period starts. A digital clock, for example, shows the current period, and not an instant. If you want to refer to the instant, you can use the words noon and midnight.