IRAC [3.6] − [4.5] / [5.8] − [8.0] diagram for the sample of 316 sources with photometric errors <0.2 mag in all bands (black dots) and the selected Class I (red squares) and Class II (green circles) candidates using the criteria given in the text. The location of the three sources A, B and C are marked with blue star symbols. The direction and size of the reddening vector for A_K = 3 mag is according to empirical relations for the IRAC bands by Indebetouw et al. (2005).