Mannequin Control Rig -- Foot Roll setup


I was checking out the mannequin control rig and saw the setup for the footroll. I believe the end results make sense in the fact that the LeftBallControl ultimately controls the position of the IK effector so the LeftBallControl and LeftFootCtrl can drive the positions simultaneously. However I am tripped up on the process used to achieve that result. Could anyone explain what is happening with the Make Relative and Multiply nodes?