Controls
The Controls tab displays all of the User Data for the selected component. If the component contains multiple objects with User Data, the attributes for each object will be shown in a separate group with the object's name.
The Controls tab lists all objects containing user data for the selected component. In the image above, the Arm component is selected, and you can see that the Clavicle, Hand, IK Arm, and Pole Vector all have user data, and each in their own separate groups.