Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Object
JOINT_OBJECT
Parameter: Connect Selection
JOINT_MOGRAPH_SELECTION_CONNECT
Parameter: Reference Axis
JOINT_REFERENCE
Parameter: Attachment
JOINT_APPLICATION
Parameter: Index
JOINT_POINT
Parameter: Map
JOINT_POINT_SELECTION
Parameter: Region Of Influence
JOINT_REGION
Parameter: Shape Conservation
JOINT_POINT_SELECTION_SHAPE_CONSERVATION
Parameter: Damping
JOINT_POINT_SELECTION_SHAPE_CONSERVATION_DAMPING
Parameter: Pin to World
JOINT_PIN_TO_WORLD
Parameter: Selection
JOINT_MOGRAPH_SELECTION_PIN