This profile cannot be used for the front of treads. Please choose a profile composed of a closed loop of lines with exactly one lines coincident with the y-axis. This lines will define the connection of this profile to the tread. 
   Namespace:   Autodesk.Revit.DB  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 2015.0.0.0 (2015.0.0.0) 
Syntax
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