Programs sometimes fail because a command outside the operation being performed interferes with a point inside the operation. Testing the priority of a point helps prevent this from happening.

If numerous tasks are being performed in the program, testing point priority levels is one method of preventing those tasks from interfering with each other.

Example

200  IF (SFAN.EQ.@EMER) THEN ON(@EMER,RFAN)

This statement tests SFAN to determine if it's at EMER priority before turning ON RFAN. If SFAN is at EMER priority, RFAN will be command ON.