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

{
  // search all single edges that intersect the data extent
  using (ArcGIS.Core.Data.Analyst3D.TinEdgeCursor edgeCursor = tinDataset.SearchEdges(null))
  {
    while (edgeCursor.MoveNext())
    {
      using (ArcGIS.Core.Data.Analyst3D.TinEdge edgeCurrent = edgeCursor.Current)
      {
        // do something with the edge
      }
    }
  }

  // search within an extent
  ArcGIS.Core.Data.Analyst3D.TinEdgeFilter edgeFilter = new ArcGIS.Core.Data.Analyst3D.TinEdgeFilter();
  edgeFilter.FilterEnvelope = envelope;
  using (ArcGIS.Core.Data.Analyst3D.TinEdgeCursor edgeCursor = tinDataset.SearchEdges(edgeFilter))
  {
    while (edgeCursor.MoveNext())
    {
      using (ArcGIS.Core.Data.Analyst3D.TinEdge edgeCurrent = edgeCursor.Current)
      {
        // do something with the edge
      }
    }
  }

  // search all "inside" edges
  edgeFilter = new ArcGIS.Core.Data.Analyst3D.TinEdgeFilter();
  edgeFilter.FilterType = ArcGIS.Core.Data.Analyst3D.TinFilterType.InsideDataArea;
  using (ArcGIS.Core.Data.Analyst3D.TinEdgeCursor edgeCursor = tinDataset.SearchEdges(edgeFilter))
  {
    while (edgeCursor.MoveNext())
    {
      using (ArcGIS.Core.Data.Analyst3D.TinEdge edgeCurrent = edgeCursor.Current)
      {
        // do something with the edge
      }
    }
  }

  // search for hard edges
  edgeFilter = new ArcGIS.Core.Data.Analyst3D.TinEdgeFilter();
  edgeFilter.FilterByEdgeType = true;
  edgeFilter.EdgeType = ArcGIS.Core.Data.Analyst3D.TinEdgeType.HardEdge;
  using (ArcGIS.Core.Data.Analyst3D.TinEdgeCursor edgeCursor = tinDataset.SearchEdges(edgeFilter))
  {
    while (edgeCursor.MoveNext())
    {
      using (ArcGIS.Core.Data.Analyst3D.TinEdge edgeCurrent = edgeCursor.Current)
      {
        // do something with the edge
      }
    }
  }
}

{
  // nodes of the edge
  var nodes = edge.Nodes;

  // edge geometry
  polyline = edge.ToPolyline();
  // edge length
  var length = edge.Length;
  // is the edge "inside"
  var isInsideEdge = edge.IsInsideDataArea;
  // edge type - regular/hard/soft
  var edgeType = edge.EdgeType;

  // get next (clockwise) edge in the triangle
  var nextEdge = edge.GetNextEdgeInTriangle();
  // get previous (anti-clockwise) edge in the triangle
  var prevEdge = edge.GetPreviousEdgeInTriangle();

  // get opposite edge
  var oppEdge = edge.GetNeighbor();

  // get left triangle
  var leftTriangle = edge.LeftTriangle;
  // get right triangle
  var rightTriangle = edge.RightTriangle;
}