NUVrJ diagram of galaxies between z = 2.5 and 6 (with their density distribution colour-coded in grey shades). The red solid line divides active and passive regions (see Eq. (2)), while red dashed lines are shifted by ±0.5 mag from that border, to give a rough estimate of the width of the green valley, that is, the separation between active and passive clumps. The red (blue) cross in the top-left (bottom-right) corner shows the typical uncertainties σ_NUV−r and σ_r−j of passive (active) galaxies at . We also compare our fiducial estimates (based on the nearest observed filter) with colours directly derived from the template SEDs: a solid contour encloses 90% of the former distribution, while a dashed line represents the 90% envelope for the latter.