public enum WktImportFlags : System.Enum, System.IComparable, System.IConvertible, System.IFormattable, System.ISpanFormattable  

// create a point with z, m
MapPoint point = MapPointBuilderEx.CreateMapPoint(
         100, 200, 300, 400, SpatialReferences.WebMercator);

// set the flags
WktExportFlags wktExportFlags = WktExportFlags.WktExportDefaults;
WktImportFlags wktImportFlags = WktImportFlags.WktImportDefaults;

// export and import
string wktString = GeometryEngine.Instance.ExportToWKT(wktExportFlags, point);
MapPoint importPoint = GeometryEngine.Instance.ImportFromWKT(
      wktImportFlags, wktString, SpatialReferences.WebMercator) as MapPoint;

double x = importPoint.X;       // x = 100
double y = importPoint.Y;       // y = 200
bool hasZ = importPoint.HasZ;   // hasZ = true
double z = importPoint.Z;       // z = 300
bool hasM = importPoint.HasM;   // hasM = true
double m = importPoint.M;       // m = 400

// export without z
WktExportFlags exportFlagsNoZ = WktExportFlags.WktExportStripZs;
wktString = GeometryEngine.Instance.ExportToWKT(exportFlagsNoZ, point);
importPoint = GeometryEngine.Instance.ImportFromWKT(
  wktImportFlags, wktString, SpatialReferences.WebMercator) as MapPoint;

x = importPoint.X;        // x = 100
y = importPoint.Y;        // y = 200
hasZ = importPoint.HasZ;  // hasZ = false
z = importPoint.Z;        // z = 0
hasM = importPoint.HasM;  // hasM = true
m = importPoint.M;        // m = 400

// export without m
WktExportFlags exportFlagsNoM = WktExportFlags.WktExportStripMs;
wktString = GeometryEngine.Instance.ExportToWKT(exportFlagsNoM, point);
importPoint = GeometryEngine.Instance.ImportFromWKT(
  wktImportFlags, wktString, SpatialReferences.WebMercator) as MapPoint;

x = importPoint.X;        // x = 100
y = importPoint.Y;        // y = 200
hasZ = importPoint.HasZ;  // hasZ = true
z = importPoint.Z;        // z = 300
hasM = importPoint.HasM;  // hasM = false
m = importPoint.M;        // m = Nan

// export without z, m
wktString = GeometryEngine.Instance.ExportToWKT(
  exportFlagsNoZ | exportFlagsNoM, point);
importPoint = GeometryEngine.Instance.ImportFromWKT(
  wktImportFlags, wktString, SpatialReferences.WebMercator) as MapPoint;

x = importPoint.X;        // x = 100
y = importPoint.Y;        // y = 200
hasZ = importPoint.HasZ;  // hasZ = false
z = importPoint.Z;        // z = 0
hasM = importPoint.HasM;  // hasM = false
m = importPoint.M;        // m = Nan

// create a polyline
List<Coordinate2D> coords = new List<Coordinate2D>
{
  new Coordinate2D(0, 0),
  new Coordinate2D(0, 1),
  new Coordinate2D(1, 1),
  new Coordinate2D(1, 0)
};

Polyline polyline = PolylineBuilderEx.CreatePolyline(
            coords, SpatialReferences.WGS84);

WkbExportFlags wkbExportFlags = WkbExportFlags.WkbExportDefaults;
WkbImportFlags wkbImportFlags = WkbImportFlags.WkbImportDefaults;

// export and import
byte[] buffer = GeometryEngine.Instance.ExportToWKB(wkbExportFlags, polyline);
Geometry geometry = GeometryEngine.Instance.ImportFromWKB(
               wkbImportFlags, buffer, SpatialReferences.WGS84);
Polyline importPolyline = geometry as Polyline;


// alternatively, determine the size for the buffer
int bufferSize = GeometryEngine.Instance.GetWKBSize(wkbExportFlags, polyline);
buffer = new byte[bufferSize];
// export
bufferSize = GeometryEngine.Instance.ExportToWKB(
                wkbExportFlags, polyline, ref buffer);
// import
importPolyline = GeometryEngine.Instance.ImportFromWKB(
         wkbImportFlags, buffer, SpatialReferences.WGS84) as Polyline;