public enum GeoCoordinateType : System.Enum, System.IComparable, System.IConvertible, System.IFormattable  

SpatialReference sr = SpatialReferences.WGS84;
SpatialReference sr2 = SpatialReferences.WebMercator;

// create some points
MapPoint point0 = MapPointBuilderEx.CreateMapPoint(0, 0, sr);
MapPoint point1 = MapPointBuilderEx.CreateMapPoint(10, 20, sr);
MapPoint point2 = GeometryEngine.Instance.Project(point1, sr2) as MapPoint;
MapPoint pointEmpty = MapPointBuilderEx.CreateMapPoint(sr);
MapPoint pointwithNoSR = MapPointBuilderEx.CreateMapPoint(1, 1);
MapPoint pointZM = MapPointBuilderEx.CreateMapPoint(1, 2, 3, 4, sr);

// convert to MGRS
ToGeoCoordinateParameter mgrsParam = 
         new ToGeoCoordinateParameter(GeoCoordinateType.MGRS);
// 31NAA6602100000
string geoCoordString = point0.ToGeoCoordinateString(mgrsParam);

// use the builder to create a new point from the string.
// Coordinates are the same 
// outPoint.x = 0; outPoint.Y = 0
MapPoint outPoint = 
      MapPointBuilderEx.FromGeoCoordinateString(
                geoCoordString, sr, GeoCoordinateType.MGRS);

// 32QPH0460911794
// outPoint.X = 10; outPoint.Y = 20
geoCoordString = point1.ToGeoCoordinateString(mgrsParam);             
outPoint = MapPointBuilderEx.FromGeoCoordinateString(
           geoCoordString, sr, GeoCoordinateType.MGRS);

// z, m are not transformed
// outPoint.X = 1; outPoint.Y = 2; outPoint.Z = Nan; outPoint.M = Nan;
geoCoordString = pointZM.ToGeoCoordinateString(mgrsParam);
outPoint = MapPointBuilderEx.FromGeoCoordinateString(
  geoCoordString, sr, GeoCoordinateType.MGRS);

// set the number of digits to 2 and convert
// 32QPH0512
// outPoint.X = 10; outPoint.Y = 20
mgrsParam.NumDigits = 2;
geoCoordString = point1.ToGeoCoordinateString(mgrsParam);             
outPoint = MapPointBuilderEx.FromGeoCoordinateString(
  geoCoordString, sr, GeoCoordinateType.MGRS);     


// convert to UTM
ToGeoCoordinateParameter utmParam = 
     new ToGeoCoordinateParameter(GeoCoordinateType.UTM);
// 31N 166021 0000000
geoCoordString = point0.ToGeoCoordinateString(utmParam);
// 32Q 604609 2211793
geoCoordString = point1.ToGeoCoordinateString(utmParam);        

// convert to DMS
ToGeoCoordinateParameter dmsParam = 
  new ToGeoCoordinateParameter(GeoCoordinateType.DMS);
// 00 00 00.00N 000 00 00.00E
geoCoordString = point0.ToGeoCoordinateString(dmsParam);
// 20 00 00.00N 010 00 00.00E
geoCoordString = point1.ToGeoCoordinateString(dmsParam);        

// convert to DDM
ToGeoCoordinateParameter ddmParam = 
  new ToGeoCoordinateParameter(GeoCoordinateType.DDM);
// 00 00.0000N 000 00.0000E
geoCoordString = point0.ToGeoCoordinateString(ddmParam);
// 20 00.0000N 010 00.0000E
geoCoordString = point1.ToGeoCoordinateString(ddmParam);        

// convert to DD
ToGeoCoordinateParameter ddParam = 
  new ToGeoCoordinateParameter(GeoCoordinateType.DD);
// 00.000000N 000.000000E
geoCoordString = point0.ToGeoCoordinateString(ddParam);
// 20.000000N 010.000000E
geoCoordString = point1.ToGeoCoordinateString(ddParam);