The dashed red NT is also shown in an extended region of the PES in Fig. . The corridor for this NT is quite small. A boundary is the dashed blue singular NT through VRI point X1 on the left, but the other boundary is the blue singular NT through VRI point X2. It connects the minimum, Min, directly to X2 and the maximum, Max. Its other branch leads from X2 to the desired SP2, but in a large arc. The dashed red NT lies above and to the right of the dashed blue boundary, and below and to the left of the solid blue NT. Near the shoulder, Sh, all NTs come close to each other but do not cross, compare also Fig. of ref. where a similar situation is described.