  The 2-quark back-angle scattering mechanism is shown to reproduce main
features of high-energy $hh$ flavor-exchange reactions. Prospects for reduction
of the reaction matrix element to a form of convolution of hadron wave
functions with the hard scattering kernel are discussed. Wave function models
suitable for convolution with the kernel, which is singular at small $x$, and
the emerging form-factor types, are discussed.
