Parallax zero-point differences versus colour and ecliptic latitude of sources with derived parallaxes (RGs, RRLs, RCs, EWs, and RGBs) located at |b| ⩽ 20° (a) and |b| > 20° (b) with five-parameter solutions. The dots with error bars represent the weighted mean parallax differences for each bin across different samples. The large error bars for RRLs (black) are attributed to the limited sample size. The grey dashed line indicates a parallax difference of zero.