start date

The start date for any data is the point in time when that data begins to be valid in the real world. It is naturally paired with the end date, which reflects the end of that same data's validity.

The date concerns the beginning of real-world validity. A value can be entered before that time as a projection or afterward as information about a past condition.

Together with the end date, it bounds the period for which the value applies. The input date instead identifies when the information was entered.