Found:

Gamma-marking

SYNTAX: mechanism which assigns the feature [+gamma] to empty categories that are properly governed. For chains terminating in an argument position, it is assumed that gamma-marking takes place at S-structure, while for chains terminating in a non-argument position it is assumed to take place at LF. EC's that are not properly governed receive the feature [-gamma] by default. In this way, applying the ECP means checking whether an EC has the feature [+gamma] at LF.

LIT.	Chomsky, N. (1986b) Lasnik, H. and M. Saito (1984)