io_dwg/description/Obasecurve.hParameters are accessed with cinema::C4DAtom::GetParameter() and cinema::C4DAtom::SetParameter(). See Parameters.
Parameter: Curve Type
BASECURVE_TYPEBASECURVE_TYPE_UNKNOWNBASECURVE_TYPE_NURBSBASECURVE_TYPE_POLYNOMIALBASECURVE_TYPE_LINEBASECURVE_TYPE_CIRCULARBASECURVE_TYPE_CONICBASECURVE_TYPE_COMPOSITEParameter: Make NURBS
BASECURVE_MAKENURBSParameter: Output
BASECURVE_OUTPUTBASECURVE_OUTPUT_LINEARBASECURVE_OUTPUT_BSPLINEBASECURVE_OUTPUT_BEZIERBASECURVE_OUTPUT_CONVERTParameter: Subdivisions
BASECURVE_SUBParameter: Dimension
BASECURVE_FLATNESSBASECURVE_PLANARBASECURVE_NONPLANARParameter: Enable
BASECURVE_TESTONParameter: Position
BASECURVE_TESTPOINT