Color magnitude diagram (CMD) of NGC 6397 Gaia DR2 data, after different filtering steps. The blue points indicate the stars that failed the PM error, astrometric and photometric flags, maximum projected radius and PM filters. The green points the stars that passed these 3 filters but are offset from the CMD. The red points show the Gaia sample of stars after the previous filters and subsequent CMD filtering, color-coded from red to dark red, according to increasing star counts.