r−W1 vs. g−r colour–colour plots illustrating how WISE helps in identifying 0.6 ≤ z_spec ≤ 1.0 ELGs. Left panel: BC03 stellar population models; models with SFH τ = 5,10 Gyr (SFH τ = 0.05,1.0 Gyr, respectively) are representative of ELGs (LRGs, respectively); all models are dust-free (E(B−V) = 0); and the reddening due to the dust (E(B−V) = 0.2) is illustrated with the arrow in the top left corner. To guide the eye, we indicate with blue shading the approximate locus where 0.6 ≤ z_spec ≤ 1.0 ELGs are expected to lie according to those models. Middle panel: SDSS objects in the VVDS/F22 survey (17.5 mag <i< 22.5 mag), binned in z_spec; the hatched region is for stars. Right panel: SDSS 0.6 ≤ z_spec ≤ 1.0 galaxies in the VIPERS survey (i< 22.5 mag), binned in total [Oii] luminosity. In the middle and right panels, we plot the region including 68% of the data for each bin.