For example, say the caveat logic is based on a user's age. It is more complex than that, but lets say the expression is

age < 18

. We pass in the user's age as part of the context and would want that permission check to return false once the user is > 18. However, the relationship should just never be created if the user is over 18 to begin with. The context data is more dynamic and we don't want to duplicate the caveat logic within application code.