Density-mapped distribution of the LPV candidates from the SOS table in the ⟨Δλ⟩_RP vs. G_BP − G_RP plane. Density contour lines are displayed in the left panel to highlight patterns in the diagram. In the right panel, sources spectroscopically identified in the literature as O-rich (blue), C-rich (red), or S-stars (green) are displayed on top of the data from the SOS table. Random artificial errors −0.5 ≤ ε ≤ 0.5 have been applied to ⟨Δλ⟩_RP for visualisation purposes, in order to smooth out the artificial clustering of that parameter around a discrete set of value.