Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Bevel Mode
MDATA_BEVEL_MASTER_MODEParameter: Offset Mode
MDATA_BEVEL_OFFSET_MODEParameter: Offset
MDATA_BEVEL_RADIUSParameter: Subdivision
MDATA_BEVEL_SUBParameter: Depth
MDATA_BEVEL_DEPTHParameter: Depth
MDATA_BEVEL_SHAPING_EXTRParameter: Limit
MDATA_BEVEL_LIMITParameter: Extrusion
MDATA_BEVEL_EXTRUSIONParameter: Max Angle
MDATA_BEVEL_POLY_ANGLEParameter: Preserve Groups
MDATA_BEVEL_GROUPParameter: Shape
MDATA_BEVEL_SHAPING_MODEParameter: Tension
MDATA_BEVEL_SHAPING_TENSIONParameter: User Shape
MDATA_BEVEL_SHAPING_SPLINEParameter: Profile Spline
MDATA_BEVEL_SHAPING_SPLINE_LINKParameter: Profile Plane
MDATA_BEVEL_SHAPING_SPLINE_PLANEParameter: Symmetry
MDATA_BEVEL_SHAPING_SYMMETRYParameter: Constant Cross Section
MDATA_BEVELL_SHAPING_CONSTANTParameter: Mitering
MDATA_BEVEL_MITERINGParameter: Ending
MDATA_BEVEL_CORNER_ENDINGParameter: Partial Rounding
MDATA_BEVEL_PROUNDING_TYPEParameter: Corner N-gons
MDATA_BEVEL_CORNER_NGONParameter: Rounding N-gons
MDATA_BEVEL_ROUNDING_NGONParameter: Phong Break Rounding
MDATA_BEVEL_SELECTION_PHONG_BREAKParameter: Phong Break Miters
MDATA_BEVEL_SELECTION_PHONG_BREAK_M