[…] we have two notions of GF relevant to LF: GF-θ and GF-θ-bar, where the former is the notion relevant to assigning θ-role and the latter is relevant to LF (if at all) only in other ways. GF-θ is represented at D-structure, GF-θ-bar at S-structure. - Chomsky (1993), a pag.44