To find all SPs, you have to choose an appropriate direction in the corresponding corridor. For example, a branch of the thick black NT (direction f = 1 √ 2 (1, 1)) connects SP1 to M via Sh, which leads to SP4. A branch of the magenta NT (f =(1,0)) connects SP3 with M and goes to SP5. Incidentally, it is not necessary to follow the specified NT exactly within a corridor, since a neighboring NT also leads to the same next stationary point.