Syntactic Theory

M-command (Maximal command)

Node c-commands node if and only if

i) does not dominate ; and

ii) every X dominating also dominates , where X is understood as a maximal projection.

M-command is a relaxed version of c-command. Consider the above tree. By the definitions of m-command, we can say that X⁰ m-commands the following constituents: YP, X' ZP. All we have to do is follow the projection line of X⁰ up to its maximal projection (XP) and collect all the constituents that XP dominates. This way, we get the m-command domain of X⁰.
Note that X⁰ does not m-command WP, since it is the lower segment of XP that is relevant for m-command.