Example of a subtracted template construction of Ca⁺ at an atmospheric temperature of 4000 K. The upper panel shows the transmission spectrum with all species included (R_all), while in the middle panel Ca⁺ has been removed as an opacity species The lower panel depicts the final template, created by subtracting the transit depths of the spectrum of the middle panel from the top-panel one (orange line). Additionally, the single species template from Fig. 1 is shown for comparison (blue line).