K_s vs. H − K_s for NIR sources towards the five areas (or subclusters) selected in the SofI field of view. Sources with a JHK_s colour excess (and H − K_s< 1) are marked by blue squares, sources with a JH(HK_s) [4.5] colour excess (and H − K_s< 1) are marked by red squares, other sources are marked by black squares (small squares for H − K_s ≥ 1). The ZAMS is also drawn in each diagram, whereas an arrow in the first box from left marks an extinction A_V = 20 mag. The sources discussed in the text are labelled, as well.