 Complete the following phrase:  The Royal Rumble is an annual gimmick pay-per-view, produced every January by the World Wrestling Federation WWF, now WWE since 1988. It is one of the promotions original four pay-per-views, along with WrestleMania, SummerSlam, and Survivor Series, later dubbed the Big Four. It is named after the Royal Rumble match, a modified battle royal in which the participants enter at timed intervals instead of all beginning in the ring at the same time. The match generally features 30 wrestlers. As the WWF World Heavyweight Championship had been vacated, the vacant title became the prize of the 1992 Royal Rumble match. 1992 was the fifth event in the Royal Rumble chronology. It was the first of only two times in which the promotions world championship was the prize of the Royal Rumble matchthe second occurred at the 