Gaia colour–magnitude diagram of our population of DA and non-DA white dwarfs, shown as yellow dots in the left panel. Highlighted in blue are those objects at distances d > ;250 pc. Assuming a limiting magnitude of G_lim = 19.5, only those brighter than M_G < 12.5 (horizontal red line) are observable. The cooling track for a 1.05 M_⊙ white dwarf (black line) is adopted as our lower selection function limit. For a given distance, only objects (marked in dark blue) at the left of the corresponding colour value (vertical red line) contribute to the final spectral distribution. The white dwarfs selected for building our spectral distribution are highlighted in red in the right panel. Objects above or below the cooling track for a 0.51 M_⊙ helium-rich and a 1.05 M_⊙ hydrogen-rich white dwarf, respectively, were discarded.