  It has been suggested that parton distributions in coordinate space, so
called Ioffe-time distributions, provide a more natural object for
non-perturbative methods compared to the usual momentum distributions. In this
paper we argue that the shape of experimentally determined Ioffe-time
distributions of quarks in a nucleon target clearly indicates separation of
longitudinal scales, which is not easily recognizable in terms of conventional
longitudinal momentum space considerations. We demonstrate how to use this
observation to determine parton distributions, using non-perturbative
information about the first few moments and the Regge asymptotics at small $x$.
