If more than one interrupt or exception is pending at an instruction boundary, the processor services one of them at a time. The priority among classes of interrupt and exception sources is shown in Table 9-2. The processor first services a pending interrupt or exception from the class that has the highest priority, transferring control to the first instruction of the interrupt handler. Lower priority exceptions are discarded; lower priority interrupts are held pending. Discarded exceptions will be rediscovered when the interrupt handler returns control to the point of interruption.