public class CIMGeometricEffectOffset : CIMGeometricEffect, System.ComponentModel.INotifyPropertyChanged, System.Xml.Serialization.IXmlSerializable  

/// <summary>
/// Create a line symbol with a dash and two markers.<br/>          
/// This line symbol comprises three symbol layers listed below: 
/// 1. A solid stroke that has dashes.
/// 1. A circle marker.
/// 1. A square marker.
/// ![LineSymbolTwoMarkers](https://ArcGIS.github.io/arcgis-pro-sdk/images/Symbology/line-dash-two-markers.png)
/// </summary>
{
  //Create a line symbol with a dash and two markers.
  //Note: Run withing QueuedTask
  CIMLineSymbol dash2MarkersLine = new CIMLineSymbol();
  var mySymbolLyrs = new CIMSymbolLayer[]
        {
              new CIMSolidStroke()
              {
                  Color = ColorFactory.Instance.BlackRGB,
                  Enable = true,
                  ColorLocked = true,
                  CapStyle = LineCapStyle.Round,
                  JoinStyle = LineJoinStyle.Round,
                  LineStyle3D = Simple3DLineStyle.Strip,
                  MiterLimit = 10,
                  Width = 1,
                  CloseCaps3D = false,
                  Effects = new CIMGeometricEffect[]
                  {
                      new CIMGeometricEffectDashes()
                      {
                          CustomEndingOffset = 0,
                          DashTemplate = new double[] {20, 10, 20, 10},
                          LineDashEnding = LineDashEnding.HalfPattern,
                          OffsetAlongLine = 0,
                          ControlPointEnding = LineDashEnding.NoConstraint
                      },
                      new CIMGeometricEffectOffset()
                      {
                          Method = GeometricEffectOffsetMethod.Bevelled,
                          Offset = 0,
                          Option = GeometricEffectOffsetOption.Fast
                      }
                  },
              },
              CreateCircleMarkerPerSpecs(),
              CreateSquareMarkerPerSpecs()
    };
  dash2MarkersLine.SymbolLayers = mySymbolLyrs;

  static CIMMarker CreateCircleMarkerPerSpecs()
  {
    var circleMarker = SymbolFactory.Instance.ConstructMarker(ColorFactory.Instance.BlackRGB, 5, SimpleMarkerStyle.Circle) as CIMVectorMarker;
    //Modifying the marker to align with line
    //First define "markerplacement"
    CIMMarkerPlacementAlongLineSameSize markerPlacement = new CIMMarkerPlacementAlongLineSameSize()
    {
      AngleToLine = true,
      Offset = 0,
      Endings = PlacementEndings.Custom,
      OffsetAlongLine = 15,
      PlacementTemplate = new double[] { 60 }
    };
    //assign the markerplacement to the marker
    circleMarker.MarkerPlacement = markerPlacement;
    return circleMarker;
  }
  static CIMMarker CreateSquareMarkerPerSpecs()
  {
    var squareMarker = SymbolFactory.Instance.ConstructMarker(ColorFactory.Instance.BlueRGB, 5, SimpleMarkerStyle.Square) as CIMVectorMarker;
    CIMMarkerPlacementAlongLineSameSize markerPlacement2 = new CIMMarkerPlacementAlongLineSameSize()
    {
      AngleToLine = true,
      Endings = PlacementEndings.Custom,
      OffsetAlongLine = 45,
      PlacementTemplate = new double[] { 60 },
    };
    squareMarker.MarkerPlacement = markerPlacement2;
    return squareMarker;
  }
}