Reference days definition is needed for the algorithm when scheduling old movies. Depending on your needs and way of programming, a day can be referenced to itself, or to another day.

For example, the weekend days are usually referenced to themselves, and non-weekend days are all referenced to Thursday.

Let’s consider that Monday’s reference is Thursday. This means that when generating the schedule for Monday, the algorithm will look how old films played last Thursday and will schedule them according to the admissions/profit they had on Thursday.