It is a tricky task to place labels on a dotty star map without creating to many overlaps, and especially overlaps with other labels are very annoying. Therefore PP3 tries to avoid that.
It does so by using a penalty algorithm: It tests the eight windrose positions around the respective object, and calculates the resulting overlaps for each position. The overlaps are counted as penalties. The position with the smallest penalty value is chosen. In very bad cases when the penalties exceed a certain threshold, the label is not printed at all.
All of this can be overruled by the user, but normally the standard behaviour is good enough. So read this section only if you are really keen to know how it works.