Cutback or extension at element curve end. 
   Namespace:   Autodesk.Revit.DB.Structure.StructuralSections  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 19.0.0.0 (19.0.0.405) 
  Since:  2018 
  Namespace:   Autodesk.Revit.DB.Structure.StructuralSections  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 19.0.0.0 (19.0.0.405) 
  Since:  2018