The lifetime of a case is the period of time between the case's start and end dates, inclusive.
Each case may bear an actual or expected start date; if an actual start date is present then it is used as the start of the case, other- wise the expected start date will be used.
Similarly, a case may have an actual end date and/or an expected date, which governs the end date of the case's lifetime (with the actual date taking precedence over any expected date).
A case without an end date is known as an "open-ended" case. A determination for an open-ended case will thus be an open-ended determination; and the final coverage period in that determination will be open-ended too.