Final answer:
Nonmaskable interrupts are used for critical events like unrecoverable memory errors, which cannot be ignored by the processor.
Step-by-step explanation:
The Nonmaskable interrupts are reserved for events such as unrecoverable memory errors. Unlike maskable interrupts, which can be turned off by the processor, nonmaskable interrupts are given higher priority because they report critical hardware issues that must be dealt with immediately.
An example would be when there is a parity error in the system's memory, indicating that data may be corrupted.