r, (r–i) OmegaCAM CMD for the X-Shooter sample (yellow stars) with sources ≳10 Myr (isochrone highlighted in blue) pinpointed with green circles (CMD−old). Sources with a disc within 1 degree of the centre of the Orion Nebula Cluster according to Spitzer photometry (Megeath et al. 2012) are displayed as dark grey circles. Only sources brighter than 17.5 mag are shown. The solid lines show the location of 0.1, 0.5, 1, 3, 10, 20, and 30 Myr PISA PMS isochrones (Tognelli et al. 2011).