One-dimensional diagram of the relation between the VGOS group delay positions (blue dots) and the locations of the radio emission in individual bands (red rhombuses). Four scenarios are shown: the location of the radio emission in band A, B, C, or D as marked by k_A|B|C|D is offset by 0.1 mas with respect to the locations in the other three bands, which are located at the origin marked by k₀. The VGOS group delay positions are shown as blue dots: for example, is where the VGOS group delay position is located when the location of the radio emission in band D is offset by 0.1 mas with respect to the other three bands.