For a manual start, AUTO IGN is set to SINGLE which alternates between igniters 1 and 2 after every second ground start. STBY IGN is set to NORM which means the AC power system supplies power to the selected igniters (as determined by the position of the AUTO IGN switch). If the STBY IGN switch is set to either 1 or 2 then "..standby power system supplies power continuously to related igniter." I agree that setting AUTO IGN to BOTH would seem to be a more logical way to achieve this but I am simply relating the procedure we have in place.
I am theorising that this might be a way to overcome some sort of igniter-related problem to achieve a successful start but, as per my originial question, I don't see why this would not also be applicable to the RR Rb211's?
LH