Mik239 posted at 9:21AM Thu, 17 May 2018 - #4330211

Because 'pm' starts with 12:00pm, 11:59am + 1 = 12:00pm, 11:59pm + 1 = 12:00am

https://en.wikipedia.org/wiki/12-hour_clock

Yes I understand that now, but it would be more logical and less confusing if it was expressed as 00:00am to 11:59am, and then 00:00pm to 11.59pm.