General
The Special Controls window is used to configure special movements of control surfaces, that are atypical of their normal movement/function. These special behaviors are commonly used for Control Augmentation and are generally found on aircraft with computer controlled control systems. High-maneuverability fighters, in particular, make heavy use of special controls in certain flight regimes.
X-Plane only models a general set of special control behaviors, mostly based on control inputs, or as a function of another control surface deflection. More advanced control surface behaviors, with bounded operating domains are not accounted for here. X-Plane's plug-in SDK allows for more customization if required. See widget descriptions and pop-up tooltips for more info about each setting. Also see Modeling Geometry > Control surfaces for more information about '-1 and -2' control surface sets.