Target Fragmentation in Semi-Inclusive DIS: Fracture Functions, Cut Vertices and the OPE

We discuss semi-inclusive Deep Inelastic Scattering (DIS) in the z -> 1 limit, in particular the relationship between fracture functions, generalised cut vertices and Green functions of the composite operators arising in the OPE. The implications, in the spin-polarised case, for testing whether the "proton spin" effect is target-independent are explored. Explicit calculations in (phi^3)_6 theory are presented which are consistent with our observations.