Template of neutral iron computed at two different values for the surface gravity, g, plotted against itself (top panel) and their relative differences (bottom panel). To first order, a change in gravity can be represented by a constant scaling (dashed line, linear fit). Departures of up to 15% occur for the weakest and strongest lines, which span a multitude of pressure scale heights. However, we find that they cause differences in the strength of the cross-correlation of no more than 0.5%.