For OM this CCF describes the missalignment between the OM optical axes and the star tracker. It is used in mission planning to predict the position of Field Acquisition Stars and targets.
SAS uses this CCF in the computation of astronomical coordinates of the detected sources.
The reference point for the boresight in the OM detector is defined as the lower left edge of pixel (1025,1025) in the V-filter. (Here it is assumed that the pixels are numbered starting with 1.)