请将下面的内容翻译成中文：A routine is declared to be an event routine rather than a callable subprogram by use of the word event rather than routine in the routine definition The flow of control within an event r

一个例程被声明为事件例程而不是可调用子程序，是通过在例程定义中使用单词"event"而不是"routine"来实现的。事件例程内的控制流行为与普通方式相同，即控制通过返回语句传递到事件的起始点，并通过返回语句离开。典型的事件例程声明语句如下： event ARRIVAL given LOCATION and ALTITUDE event DEPARTING(DESTINATION) event ALLOCATION(SUM, PERSON1, PERSON2)