For Apex3D processing, auto-calculated trendlines can be overridden via manual input of "driftFWHMstart" and "driftFWHM-end" arguments which define the drift FWHM trendline values at drift time bin 0 and bin 200, respectively. For example, a "1-4" trendline refers to a trendline with drift FWHM value of 1 at drift time bin 1 and a drift FWHM value of 4 at drift time bin 200. To test this hypothesis, differential Apex3D processing was performed on XylE cIM multi-pass and 1-pass data using 8 variations of manually inputted trendlines and compared peptide identification with default processing (Figure ).