Priority is a measure of the relative importance of the currently executing line and allows higher priority events to interrupt lower priority events, while preventing lower priority events from interrupting higher priority events. Priority values can range from 0 (least important) to 15 (most important). The ON statement which defines the service routine for an event also allows the priority for that service to be defined. The system priority is the priority of the currently executing line and can be changed with the SYSTEM PRIORITY statement.
