Display of the full sets of vectors characterizing the astrometric position variations for the sources 0014+813, 0059+581, 1739+522, and 1334−127. Each vector connects a pair of successive (reduced) positions in the plane of the sky, as plotted in Fig. 3 for the same four sources. The vector angle is counted from north to east modulo 180°. The color indicates the epoch of the first position in the pair (see the color bar on the right-hand side of each panel). The PDF built from these sets of vectors are given as the upper edge of the shaded areas in the insets. The colored lines in the insetsshow fits to the PDF when one to five components (i.e., the preferred directions) are extracted.