Internal domain

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)   XP1 /\      /  \      UP  XP2 /\       /  \      ZP1    X'     /\      /\ / \    /  \   WP  ZP2  X1  YP           /\ / \         H   X2

Link
Utrecht Lexicon of Linguistics