... The described procedure returns the one-dimensional response distribution in PI channels, based on an input energy. The redistribution function of the MOS cameras comprises a main peak (roughly centred on the input photon energy); a lower-energy secondary peak, whose relative magnitude is inversely correlated with the photon energy, and a noise term which extends down to the detection threshold energy. Details of the current calculation are given in the CCF release note, CAL-SRN-272. ...