Colour–colour diagram, [3.6]–[4.5] vs. [5.8]–[8.0], for all Spitzer-GLIMPSE sources with measurements in the four bands, and situated within 10′ from the radio peak of the G316.80–00.05 field. The location of YSOs dominated by a disk (Class II YSOs) and by an envelope(Class I YSOs) are indicated, following Allen et al. (2004; see also Megeath et al. 2004). The sources discussed in the text, mainly candidate Class I YSOs, are identified.