Left panel: position of stars brighter than m_814W = 18.5 in the cluster NGC 6254. The red and blue circles indicate the two regions used to produce the chromosome maps of the right panel. Right panel: chromosome map of the stars inside the blue circle in the left panel (blue squares) and of the stars in between the red and blue circles (open red circles). Only stars brighter than m_814W = 16.5 (i.e., above the bottom of the RGB) are considered in the chromosome maps.