NIR colour–magnitude diagram for J,H, and Ks selected samples obtained from the Ultra-Deep sample (black points). The two oblique dashed lines correspond to the I-band limiting magnitudes of the survey i_AB = 23 on the bright end, i_AB = 24.75 on the faint end. The VVDS-Deep colour–magnitude distribution is shown as the grey points with the i_AB = 17.5 and i_AB = 24 limits indicated as long-dashed lines. We are able to extract samples that are nearly complete in spectroscopic redshift measurements, selected down to J_AB = 23, H_AB = 22.5, and Ks_AB = 22 (vertical dashed lines). The faint i-band magnitude cut imposes a loss of red objects for fainter magnitudes but it is still 80% complete down to J_AB = 24, H_AB = 23.5, and Ks_AB = 23. Typical error bars are shown at the bottom of each panel.