Found:

Internal domain

**SYNTAX: **Notion in **checking theory**. The internal domain of A is the minimal **complement domain** of A.
** EXAMPLE:** In (i), the complement domain of X (and H) is YP and everything YP dominates. The internal domain of X (and H) is just YP.

(i) XP_{1}/\ / \ UP XP_{2}/\ / \ ZP_{1}X' /\ /\ / \ / \ WP ZP_{2}X_{1}YP /\ / \ H X_{2}

LIT. | Chomsky, N. (1993) |