Difference in distances between two dominant source components measured in the S and X bands as a function of distance measured in the X band. Green points represent GPS and steep spectrum sources, red points represent flat spectrum sources. Objects included in the COINS sample are marked with blue squares, while objects rejected from the COINS sample as probable core-jet sources are marked with blue crosses. The green line denotes the median distance difference for GPS/steep spectrum sources, the red line marks the same for flat spectrum sources.