xpressocore/description/gvbool.hParameters are accessed with cinema::C4DAtom::GetParameter() and cinema::C4DAtom::SetParameter(). See Parameters.
Parameter: Function
GV_BOOL_FUNCTION_IDGV_AND_NODE_FUNCTIONGV_OR_NODE_FUNCTIONGV_XOR_NODE_FUNCTIONGV_NAND_NODE_FUNCTIONGV_NOR_NODE_FUNCTIONGV_NXOR_NODE_FUNCTIONParameter: Input
GV_BOOL_INPUTParameter: Output
GV_BOOL_OUTPUT