Found:

chain condition

SYNTAX: wellformedness condition on chains, which states that every chain (a₁,...,a_n) must contain exactly one Theta-marked position and exactly one Case-marked position. In A-chains a₁ is Case-marked and a_n is Theta-marked, while in A'-chains the lowest variable A'-bound by the operator is Case-marked, and may either be Theta-marked, or A-bind a Theta-marked position in the chain. This condition restates the case filter (or the visibility condition) and the Theta criterion in terms of chains.

LIT.	Chomsky, N. (1986b) Chomsky, N. (1986a) Chomsky, N. (1981)