User Data [update]
User Data node provides access to the color, vector and float channels that can be specified for any object in Cinema 4D. These data channels are accessed by their short name specified for object. If the data channel is not found for object then default color is used.
In example below we combine all three object channels Data1, Data2 and Data3 (with red, green and blue colors) using the Gradient Ramp node.
This node can be used to control shader properties from the object manager settings.