Date logic to hide or reveal fields if the date a customer enters is "X" number of days or months (specified by the form designer) from the current date (or maybe also a date specified by the form designer).

Useful, for example, where a customer submits a request for a review late (over 1 calendar month from the original decision date) and so must provide good reason. The "good reason" text box will appear if the date logic is met.