  The NA48/2 experiment at the CERN SPS collected in 2003 and 2004 large
samples of the decays K+- -> pi+ pi- e+- nu (Ke4+-), K+- -> pi0 pi0 e+- nu
(Ke400) and K+- -> pi0 pi0 pi+-. From the Ke4+- form factors and from the cusp
in the M00^2 distribution of the K+- -> pi0 pi0 pi+- events, the pi-pi
scattering lengths a00 and a20 could be extracted. This measurement is a
fundamental test of Chiral Perturbation Theory (ChPT). The branching fraction
and form factors of the Ke400 decay were precisely measured, using a much
larger data sample than in previous experiments. An improved measurement of the
slope parameters for the decay K+- -> pi0 pi0 pi+- showed evidence for a
non-zero value of k.
