This is a multi-purpose mocap rig. It was designed to take unknown motion capture data and retarget it onto the rig automatically.
The FK and IK systems both follow the Motion Capture system. The FK also follows the IK and the IK follows the FK.
All of the various systems are additive and can be turned on or off on demand. The FK and IK systems can be switch by simply selecting the controllers, and the manipulators will automatically switch to the appropriate mode; translation, rotation or scale.
Breathing controls can work automatically, or be animated by hand.