  We revisit the connection between generalized parton distributions in impact
parameter space and T-odd effects in single spin asymmetries of the
semi-inclusive deep inelastic process. We show that nontrivial relations can be
established only under very specific conditions, typically realized only in
models that describe hadrons as two-body bound systems and involving a
helicity-conserving coupling between the gauge boson and the spectator system.
Examples of these models are the the scalar-diquark spectator model or the
quark-target model for the nucleon, and relativistic models for the pion at the
lowest order in the Fock-space expansion.
