Trilean is a three-state Boolean. It allows you to express the following values:
Particularly useful when you want to represent a third state other than True and False, like "null" or "unset". In OutSystems this is usually accomplished by a second "helper" boolean that indicates whether the first Boolean is filled or not. Trilean provides a way to be more expressive about it.
Inspired by the great article written by Dorine Boudry. Kudos!