For clarification.. Are you saying the switch itself (the rotary portion) is identical across models (M, ML & CLS) and the circuit (the plug section) is identical as well? If so, then I guess it is the computer in the backend making the decision. Using the EPC site as reference. I know the light switch part # are read as A219 545 07 04. I know 219 is MB model, 545 is light group, what are 07 & 04 reference to? Are they the actual part number for the switch? For cross-reference purpose, would that be the #s I should check more closely with?