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

//The layer must be track aware and spatial
if (streamLayer.TrackType != TrackType.Spatial)
  return;
//Must be on QueuedTask!
//Define unique value classes same as we do for current observations
//or use "CreateRenderer(...)" to assign them automatically
CIMUniqueValueClass uvcB727Prev = new CIMUniqueValueClass()
{
  Values = new CIMUniqueValue[] { new CIMUniqueValue() {
    FieldValues = new string[] { "B727" } } },
  Visible = true,
  Label = "Boeing 727",
  Symbol = SymbolFactory.Instance.ConstructPointSymbol(
    CIMColor.CreateRGBColor(255, 0, 0), 4, SimpleMarkerStyle.Hexagon)
    .MakeSymbolReference()
};

CIMUniqueValueClass uvcD9Prev = new CIMUniqueValueClass()
{
  Values = new CIMUniqueValue[] { new CIMUniqueValue() {
    FieldValues = new string[] { "DC9" } } },
  Visible = true,
  Label = "DC 9",
  Symbol = SymbolFactory.Instance.ConstructPointSymbol(
    CIMColor.CreateRGBColor(0, 255, 0), 4, SimpleMarkerStyle.Hexagon)
    .MakeSymbolReference()
};

CIMUniqueValueGroup uvGrpPrev = new CIMUniqueValueGroup()
{
  Classes = new CIMUniqueValueClass[] { uvcB727Prev, uvcD9Prev }
};

var UVrndrPrev = new CIMUniqueValueRenderer()
{
  Fields = new string[] { "ACTYPE" },
  Groups = new CIMUniqueValueGroup[] { uvGrpPrev },
  UseDefaultSymbol = true,
  DefaultLabel = "Others",
  DefaultSymbol = SymbolFactory.Instance.ConstructPointSymbol(
    CIMColor.CreateRGBColor(185, 185, 185), 4, SimpleMarkerStyle.Hexagon)
    .MakeSymbolReference()
};
        
streamLayer.SetRenderer(UVrndr, FeatureRendererTarget.PreviousObservations);

//The layer must be track aware and spatial
if (streamLayer.TrackType != TrackType.Spatial)
  return;
//Must be on QueuedTask!
//Note: only a simple renderer with solid line symbol is supported for track 
//line renderer
var trackRenderer = new SimpleRendererDefinition()
{
  SymbolTemplate = SymbolFactory.Instance.ConstructLineSymbol(
      ColorFactory.Instance.BlueRGB, 2, SimpleLineStyle.Solid)
        .MakeSymbolReference()
};
streamLayer.SetRenderer(
     streamLayer.CreateRenderer(trackRenderer), 
       FeatureRendererTarget.TrackLines);

//The layer must be track aware and spatial
if (streamLayer.TrackType != TrackType.Spatial)
  return;
//Must be on QueuedTask!
var prev_renderer = streamLayer.GetRenderer(
    FeatureRendererTarget.PreviousObservations);

//The layer must be track aware and spatial
if (streamLayer.TrackType != TrackType.Spatial)
  return;
//Must be on QueuedTask!
var track_renderer = streamLayer.GetRenderer(
    FeatureRendererTarget.TrackLines);