Final answer:
AM/PM pre-arrival service refers to the time before midday (AM) and after midday (PM), based on the position of the Sun in relation to the local meridian. The cycle starts at midnight (12:00 AM) and runs through to the following midnight.
Step-by-step explanation:
AM/PM pre-arrival service begins with a time division based on the position of the Sun in relation to the local meridian. The term ante meridiem (AM) refers to the time before midday, indicating the hours when the Sun has not yet reached the local meridian, which is often associated with the morning hours. Once the Sun has passed the local meridian, time is designated as post meridiem (PM), reflecting the afternoon and evening hours. This cycle begins at midnight (12:00 AM) and runs throughout the day until the next midnight, starting over again.