Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Mode
MDATA_KNIFEPLANE_MODE
Parameter: Plane Mode
MDATA_KNIFEPLANE_PLANE_MODE
Parameter: Plane
MDATA_KNIFEPLANE_PLANE
Parameter: Plane Position
MDATA_KNIFEPLANE_PIVOT_POSITION
Parameter: Plane Rotation
MDATA_KNIFEPLANE_PIVOT_ROTATION
Parameter: Offset
MDATA_KNIFEPLANE_OFFSET
Parameter: Number of Cuts
MDATA_KNIFEPLANE_CONUT
Parameter: Spacing
MDATA_KNIFEPLANE_DIST
Parameter: Restrict To Selection
MDATA_KNIFEPLANE_SELECTED
Parameter: Select Cuts
MDATA_KNIFEPLANE_SELECT_CUT
Parameter: Connect Cut Edges
MDATA_KNIFEPLANE_CUTPOLYS
Parameter: Preserve N-gon Curvature
MDATA_KNIFEPLANE_NGON_CURVATURE
Parameter: Auto Snap
MDATA_KNIFEPLANE_AUTOSNAP
Parameter: Regular Slice
MDATA_KNIFEPLANE_REGULARSLICE
Parameter: Angle Constrain
MDATA_KNIFEPLANE_ANGLE_CONSTRAINT
Parameter: Angle
MDATA_KNIFEPLANE_ANGLE_CONSTRAINT_VALUE
Parameter: Realtime Cut
MDATA_KNIFEPLANE_REALTIME