Think Control Wheel Steering, or, the autopilot is always on, even when you are "hand flying".
You can tell the autopilot,what you want via buttons, or via a joystick, but it is always on.
I know, I know...
Not exactly accurate...
Probably makes more sense to those of us that remember CWS mode on the 76, or the Pitch/Turn knob on the 727.