22. The method of claim 21 wherein said step of allowing comprises the step of obtaining the reference to said second highest preference group of instructions from the table containing said first preference group of instruction contained in the control structure of the present system state by said computer; and executing said second highest preference group of instructions by said computer.
22. The method of claim 21 wherein said step of allowing comprises the step of obtaining the reference to said second highest preference group of instructions from the table containing said first preference group of instruction contained in the control structure of the present system state by said computer; and executing said second highest preference group of instructions by said computer. 23. The method of claim 22 wherein said blocking step comprises the step of ceasing to process said system signal by said computer by inhibiting the determination of the reference to said third highest preference group of instructions of said table by said computer.