If a customer is a member and the MEMBER key 95 is depressed, as exemplarily illustrated in FIG. 6, the sequence in FIG. 5 flows through STEP 101-YES (a key input is recognized), STEP 102-NO (the depressed key is not the TEMP CHANGE key 96) STEP 104-YES (the depressed key is the MEMBER key) and STEP 105-NO (the TEMP CHANGE flag FT has not been reset) to STEPS 106 and 107 wherein a logical 1 is