The first real ``trick'' employed by Method 1 makes use of the fact that above a wavelength of 400nm, the acrylic tiles are essentially transparent, with all tiles yielding the same transmission to within a couple percent almost regardless of their assigned quality. Therefore, after corrections for geometry and D2O/H2O extinction, any differences in observed prompt-peak intensities above this wavelength between PMTs, must be the result of different PMT/reflector efficiencies (for now, this will be considered as a single quantity). These relative efficiencies are thus determined from the median of values computed at different laserball positions within the AV, and the spread in these values is used as an estimate of the statistical uncertainty. These are assigned to the variables OCA_Rel400(NPMT,1) and OCA_Rel400(NPMT,1), respectively, where NPMT is the pmt number.