The stacked square root of the formal second moment (μ₂)^1/2 of the spectral trace for the ¹²CO emission lines. About 5–10 clean lines for each source were used for stacking. The square root of the second moment (μ₂)^1/2 is multiplied with * = 0.2 for sources with a larger uncertainty in the second moment. The vertical shift for respective source is: AS 205 A = 0 AU, DR Tau = –3.4 AU, RU Lup = –7.0 AU, S CrA A = –7.2 AU. For VW Cha and VZ Cha the shifts are 5.5 and 3.7 AU after multiplication with 0.2.