This clause specifies the language-defined model for hardware interrupts in addition to mechanisms for handling interrupts. An interrupt represents a class of events that are detected by the hardware or the system software. Interrupts are said to occur. An occurrence of an interrupt is separable into generation and delivery. Generation of an interrupt is the event in the underlying hardware or system that makes the interrupt available to the program.
Delivery is the action that invokes part of the program as response to the interrupt occurrence.
Some or all interrupts may be blocked. When an interrupt is blocked, all occurrences of that interrupt are prevented from being delivered. Certain interrupts are reserved. The set of reserved interrupts is implementation defined. Program units can be connected to non-reserved interrupts.