Correlation diagram for candidate C₂-DIBs (blue dots, Table B.3) and possible C₂-related DIBs (green diamonds, Table B.4), comparing them to reference C₂-DIBs (black squares, Table B.1), candidate C₂-DIBs from the literature (grey diamonds, Table B.2), possible DIBs similar to λ5849 (F5849, cyan triangles) and a comparison sample of ζ DIBs (red dots). The horizontal axis displays the normalised anticorrelation Pearson coefficient, kn₆₀₀₉, with the σ DIB λ6009 (excluding the sight lines of HD 175156 and HD 148579). The vertical axis displays the average correlation coefficient, knq_C2 (Eq. 3), with a subsample of six reference C₂ DIBs (λλ4726, 4963, 4984, 5418, 5512 and 5546). It is seen that the selection criteria (Eqs. (4,6)) discriminate well C₂ DIBs from ζ DIBs. Most C₂ DIBs and related DIBs are significantly anticorrelated with σ DIBs (kn₆₀₀₉. < 0). See Fig. 1 for a reduced version of this figure without DIB labels.