Fig. (10) (Color on line). Exotic low mass meson masses. SPES3 data [14, 8]: solid red circles; Lear data [2]: empty blue squares; Uppsala data [5]: solid green triangles. The Celsius [16] and the Cosy narrow structure mass [17] are shown by a purple empty cross. The PDG π⁰ mass [1] is introduced by a black star.