    EVENT_NULL        170 source/sched.c struct event_list *event_head = EVENT_NULL;
    EVENT_NULL        518 source/sched.c    if (event_head != EVENT_NULL)
    EVENT_NULL        940 source/sched.c          if ((the_event = ll_locate(ret)) == EVENT_NULL)
    EVENT_NULL       1192 source/sched.c          if ((the_event = ll_locate(ret)) == EVENT_NULL)
    EVENT_NULL       1467 source/sched.c    if (event_head != EVENT_NULL)
    EVENT_NULL       2562 source/sched.c    if (rov == EVENT_NULL)
    EVENT_NULL       2567 source/sched.c    while(rov != EVENT_NULL)
    EVENT_NULL       2773 source/sched.c    if (rov == EVENT_NULL)
    EVENT_NULL       2774 source/sched.c       return(EVENT_NULL);
    EVENT_NULL       2777 source/sched.c       return(EVENT_NULL);
    EVENT_NULL       2779 source/sched.c    while(rov != EVENT_NULL)
    EVENT_NULL       2790 source/sched.c    return(EVENT_NULL);
    EVENT_NULL       2805 source/sched.c    if ((list_entry = (struct event_list *)malloc(size)) == EVENT_NULL)
    EVENT_NULL       2812 source/sched.c    list_entry->next = EVENT_NULL;
    EVENT_NULL       2816 source/sched.c    if (event_head == EVENT_NULL)
    EVENT_NULL       2826 source/sched.c    while(rov->next != EVENT_NULL)
    EVENT_NULL       2841 source/sched.c    while(rov != EVENT_NULL)
    EVENT_NULL       2848 source/sched.c    event_head = EVENT_NULL;