Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Selection
MDATA_MEASURE_SELECTION
Parameter: Show
MDATA_MEASURE_VISIBLE
Parameter: New Measure
MDATA_MEASURE_NEW
Parameter: Delete Measure
MDATA_MEASURE_DELETE
Parameter: Create Object
MDATA_MEASURE_CREATEOBJECT
Parameter: 3rd Point
MDATA_MEASURE_3RD_POINT
Parameter: Measure Distance 1
MDATA_MEASURE_SHOWDIST1
Parameter: Distance 1
MDATA_MEASURE_DIST1
Parameter: Revert Direction
MDATA_MEASURE_DIR1
Parameter: Measure Distance 2
MDATA_MEASURE_SHOWDIST2
Parameter: Distance 2
MDATA_MEASURE_DIST2
Parameter: Revert Direction
MDATA_MEASURE_DIR2
Parameter: Measure Angle
MDATA_MEASURE_SHOWANGLE
Parameter: Angle
MDATA_MEASURE_ANGLE
Parameter: Revert Axis
MDATA_MEASURE_FIXROT
Parameter: Point Color
MDATA_MEASURE_COLORP
Parameter: Color 1
MDATA_MEASURE_COLOR1
Parameter: Color 2
MDATA_MEASURE_COLOR2
Parameter: Point 1 Object
MDATA_MEASURE_PNT1_LINK
Parameter: Point 1 Mode
MDATA_MEASURE_PNT1_MODE
Parameter: Point 1 Index
MDATA_MEASURE_PNT1_IDX
Parameter: Point 1 Position
MDATA_MEASURE_PNT1_VECTOR
Parameter: Point 2 Object
MDATA_MEASURE_PNT2_LINK
Parameter: Point 2 Mode
MDATA_MEASURE_PNT2_MODE
Parameter: Point 2 Index
MDATA_MEASURE_PNT2_IDX
Parameter: Point 2 Position
MDATA_MEASURE_PNT2_VECTOR
Parameter: Point 3 Object
MDATA_MEASURE_PNT3_LINK
Parameter: Point 3 Mode
MDATA_MEASURE_PNT3_MODE
Parameter: Point 3 Index
MDATA_MEASURE_PNT3_IDX
Parameter: Point 3 Position
MDATA_MEASURE_PNT3_VECTOR