Found:
head movement
SYNTAX: movement of a head, an X0, out of its projection to another head-position. EXAMPLE: in questions a finite verb may move to C0. In (i) the auxiliary will (an I, see INFL) is moved to C0, leaving a trace in I.
(i) [CP What [C willi] [IP John [I ti] buy]]?Head movement obeys the Head Movement Constraint.
| LIT. | Chomsky, N. (1986b) Rizzi, L. (1990) |