I understand it to be considered as "movable aerodynamic surface" that proven by its specific construction to facilitate that movement.
As people have described "grey" or debatable as to its inclusion.
Clearly, to design that characteristic into the component for the gain it was targeting, is covered by that wording. Loosely maybe, but definitely under some level of control that necessary "discussion" with McL team.
But not hard in definite and absolute limit, like the other two incident given as examples.