Well, if you mean like that (I'd rather use "ship space", since "world space" implies global coordinates for the entire mission), then AFAIK it'd be world's axis. Basically, if you define a model to rotate on Y-axis, then it'll rotate around the ship's Y-axis (i.e. top-down direction relative to the ship), no matter how you twist or transform the submodel itself. Yes, this does make off-axis doors and other animations hard to set up, and that's why there's so few of them. You have to express the rotation you want as a sum of two rotations around different axes. For simple angles like 30, 45 and 60 degrees this should be easy, for others might be less so, but it pretty much all boils down to high school level maths at most.