The values in the fpi10.dat-file correspond to:

M^2_{\pi\pi}  fpi  sigma_stat

The M^2_{\pi\pi} value stands for the center of the bin (the binwidth is
0.01 GeV^2). sigma_stat stands for the square root of the diagonal element 
in the covariance matrix of the statistical error.

The fpi values are undressed from FSR from pions in
the final state, using the values from ref. [26]
(which treats the pions as pointlike particles).

The fpi values are inclusive with respect to vacuum polarization in the
virtual photon (i.e., no correction has been applied).