If α in S-structure has been derived by movement of β from the position occupied by α, then we will say that α is "the trace of" β, and β is "the t-antecedent of" α. By the projection principle, the t-antecedent of α is in a non-θ position [...] If α is locally A-bound by a t-antecedent, then it is NP-trace, a non pronominal anaphor.
- Chomsky (1993), a pag.328