This document provides instructions for converting between 12-hour and 24-hour time formats. It explains that to convert a 24-hour time to 12-hour, one subtracts 12 if the hour is greater than 12 or changes 00 to 12am. When converting 12-hour to 24-hour, 12pm becomes the hour and 12am becomes 00, while other pm times have 12 added to the hour. The minutes and seconds never change between the two formats.