  The dispersive approach based only on very general principles, unitarity,
analyticity and crossing symmetry, combined with chiral counting enables to
construct fully relativistic model-independent representations of the eta and K
three-pion decays valid up to and including two-loop corrections. Here we
demonstrate the procedure on the eta->3pi^0 decay. We perform possible
matchings of our dispersive approach with the two-loop ChPT result and briefly
discuss corresponding predictions of the Dalitz plot slope parameter alpha.
