Top panel: Correlation plot showing the relation between the contrast at 2800 Å (C₂₈₀₀) and the contrast in the mean contrast in the Mg II k line (C_L). Middle panel: histograms of C₂₈₀₀. Bottom panel: Histogram of C_L. Type 1 CB is in red color, Type 2 CB is in blue, Type 3 CB is in green. In the top panel we note a global anticorrelation with a general tendency that increasing line emission leads to decreasing wing emission. The diagonal gray lines indicate the values of the ratio, R (0.25 and 0.9), which separate the three types of CBs. Black dots indicate the five CBs from paper Grubecka Litwicka et al. (2016).