Photocenter centroid variations RSE with respect to binary separation and flux ratio delineated with white contours. The red contours delineate the GOF amplitude (at levels 0.1 and 1) and the cyan contours delineate the 2 and 98% levels of the IPD_frac_multi_peak. The white hatched region shows, as discussed in the text, where the RMS of the Δη residuals could be larger than 0.1 mas, while outside this region it is always <0.1 mas.