Recall that θ-marking takes place in the configuration (5) [(i) [γ...α...β...] (ii) [γ...β...α...]] where β as well as α is an immediate constituent of γ, assuming α to have appropriate properties determined ultimately by the lexicon. There are two cases: (i) γ = ᾱ; (ii) β is the subject of α [...] In case (ii), if α θ-marks β (a position or category), let us say that the lexical head of α "indirectly θ-marks" β.
- Chomsky (1993), Pag. 38