In the following procedure, you create two Auxiliary pivots for additional control over the IK system on Mia’s Control rig. These Auxiliary objects can be used to create realistic rotation of Mia’s feet as she walks. They also make it easier to rotate Mia’s feet while creating keyframe animation.
To add Auxiliary pivots:

Producer Front (or click the Viewer window and press Ctrl-F).
or Ctrl-drag) and pan (
or Shift-drag) to see Mia’s feet. 
The selected effector is displayed with a blue (
) contour.

The Auxiliary pivot is displayed in the Viewer window as a green sphere (by default).

In the Character Controls window, the Auxiliary pivot is displayed on the left ankle cell as an X.

When you create an Auxiliary pivot, the effector is deselected as shown in the following figure and the Pivot Object mode tool (
) is automatically selected.

Producer Right.
or Shift-drag) and zoom in (
or Ctrl-drag) on Mia’s left foot. 

The context menu shows the Left Ankle effector pivot is selected.
Producer Right.
or Shift-drag) and zoom in (
or Ctrl-drag) on Mia’s left foot. 
In this tutorial, you created a Control rig, arranged the floor contact markers on the character’s feet, then created two Auxiliary pivots to control the rotation of the foot.
In the next tutorial, (Creating a Character Extension), you add a Character Extension to the Mia character.