@Cuddles: It doesn't matter what the letters technically stand for, it's a simple naming convention that is well established and easily understood - 12AM is midnight, 12PM is midday.
It does matter because there is no "simple naming convention that is well established and easily understood". Actually, that is a lie: there is and it's called the 24 hour clock and it is was created for almost exactly this reason.
In context it is usually possible to figure out whether 12am or 12pm are referring to midday or midnight (whichever one), however your arguments about the "naming convention" are just wrong, there isn't one. 12pm is arguably as much midday as it is midnight. After all, 12pm is at the end of the rest of the pm times (11:59pm => tick => 12:00pm) therefore it is obviously midnight isn't it? Except that you're claiming that it isn't...