The attendance status is based on the day - a child is either present or absent on any given day. After that, we use periods to determine when they were actually there.
If a child is not in attendance in the morning, you can mark them absent/sick. If they arrive in the afternoon, you can simply check them in. If a child is present in the morning and absent in the afternoon, we recommend leaving them as checked out - it is not necessary to mark them as absent in these situations.
At the end of the day we recommend marking any child that still does not have an attendance status as absent.