Relative endotrivial modules and endo-p-permutation modules in the Auslander-Reiten quiver

This note aims at describing the position of endo-p-permutation and relative endotrivial modules in the Auslander-Reiten quiver of a group algebra kG. The answer is that they lie at the end of their components or at relative ends, unless the Sylow subgroups are dihedral, in which case they form entire components.