Each account has zero or more account records. Each account record has an entry for a date and a medical procedure such as an appendectomy. It may also have an entry for a facility such as an operating room, and it may also have entries for items used such as gauze bandages. Each medical procedure, facility, and item has a certain cost. Some procedures require a facility.
Some procedures require one or more items.
Certain procedures, of course, may require both a facility and several items.