A mounting system comprising an incremental angular position and locking system. The compound is 9-anthrcenylmethyl-1-piperazinecarboxylate, an isocyanate derivatizing agent. A longitudinal tilt measuring system measures a longitudinal tilt of the interface from a predetermined reference position, and a corrected measured value corrected according to the longitudinal tilt measured by the longitudinal tilt measuring system is obtained. The heat shield includes an intermediate portion spanning in the circumferential direction of the fixing rotary body and movable between a shield position where the intermediate portion is disposed opposite the heater directly and a retracted position where the intermediate portion is disposed opposite the heater via the overheating suppressor.