Art. 17 provides for third way an offer can be deprived of its effect:
An offer, even if it is irrevocable, is terminated when a rejection reaches the offeror.
The lapse of a fixed time for acceptance set in the offer in general leads to a termination of the offer. By way of exception, however, the period of time can merely indicate that the offer is irrevocable under Art. 16(2)(a). Which of these legal constructs was intended by the offeror has to be determined by way of interpretation under Art. 8.