A pilot shall be relieved of all duty and reserve availability for at least 48 consecutive hours at the conclusion of an international trip that exceeds 120 hours TAFB, except for trips scheduled in accordance with Section 12.D.1.c.i.
If the trip does not exceeds 120 hours TAFB but the last duty period is an international duty period, then the buffer applies also.
You can waive the international duty periods when you bid if you want to retain the trip and slide the vacation within 48 hours of the end of the trip.