2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/86890Snake ``resonances'' are classified in terms of the invariant spin field and the amplitude dependent spin tune. Exactly at snake ``resonance'' there is no continuous invariant spin field at most orbital amplitudes.8 pages, 2 figures. Extended version of a paper for the 15th International Spin Physics Symposium, Brookhaven National Laboratory, U.S.A., 2002Accelerator Physicstext