Checking domain

Within checking theory of the Minimalist Program, the checking domain of a head A consists of everything adjoined to it, and of its specifier(s). Formally, the checking domain of a head A is defined as the minimal residue of A. The residue of A is its domain minus its complement domain.

Example
In the following structure (with a head H adjoined to X), the checking domain of X consists of UP, ZP, WP and H. The checking domain of H is UP, ZP and WP.

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

Link
Checking domain in Utrecht Lexicon of Linguistics

Reference

 * Chomsky, Noam A. 1995. The Minimalist program. Cambridge, MA: MIT Press.