Date Reference, Work Shift Setup

Here you can select whether the transactions created during the work shift is marked with a shift date that follows the start time of the work shift setup or the end time of the work shift setup.

This field is only of importance when a work shift covers two dates, that is lasts beyond 12 midnight. This field gives you the chance to control to which of the two days the work shift belongs.
You have two options you can select in this field:

End Time

Start Time