Usually, vacuum quantum number exchange is parametrized in terms of the socalled P and P' trajectories. We recall that P' is associated to the exchange corresponding to thef0 (1260) meson, built from direct channel resonances in the dual sense. In this note we want to critically review the main phenomenological results concerning P' and present some arguments showing that this singularity may not be considered on an equal footing with the ordinary Regge trajectories, i.e., p, (J), etc.