The priority may be a numeric expression and is rounded to an integer in the range of zero (the lowest priority) through fifteen (the highest priority). The default priority is zero.ON END,ON ERROR, andON TIMEOUThave higher priorities than the highest userSYSTEM PRIORITY.
Any events defined at an equal or lower priority will be logged and not executed until the system priority is lowered.
If the system priority is changed within a subprogram, it will be restored when the subprogram ends.