What is queue discipline? State three rules for queue discipline. Which of these rules appears most frequently in the four main models?

Queue discipline is the rule that determines the sequence in which arrivals will receive service. Choices include (1) FIFO, FIFS, or first-in, first-served, (2) LIFO, LIFS, or last-in, first-served, and (3) priority, such as the triage area of a hospital emergency room. FIFO is the only one assumed by the four models.