Histograms of the difference between the PA of the major-axis of the maser distribution, MA_MD, and the PA of the preferential direction of the maser PMs, PD_PM (upper panel), between MA_MD and the PA of the major-axis of the radio continuum emission, MA_RC (middle panel), and between PD_PM and MA_RC (lower panel). To produce these histograms we have selected all the POETS targets belonging to the combined subgroups N-C and N-G (see Table A.1). The histogram bin is 15° and the histogram values are normalized by the total number of considered targets. The source-average errors on the differences MA_MD −PD_PM, MA_MD −MA_RC, and PD_PM−MA_RC are 26°, 21°, and 24°, respectively.