Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: GroupA
INT_GROUPA
Parameter: GroupB
INT_GROUPB
Parameter: Distance Type
INT_DTYPE
Parameter: Distance
INT_DISTANCE
Parameter: Particle Count A
OUT_INTERACT_PARTICLECOUNT_A
Parameter: Particle Count B
OUT_INTERACT_PARTICLECOUNT_B
Parameter: Position A
OUT_INTERACT_POSITION_A
Parameter: Position B
OUT_INTERACT_POSITION_B
Parameter: Vector AB
OUT_INTERACT_VECTOR_AB
Parameter: Distance AB
OUT_INTERACT_DISTANCE_AB