Indicates if to set and get the setting for if shading surfaces should be included. 
   Namespace:   Autodesk.Revit.DB.Analysis  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 2015.0.0.0 (2015.0.0.0) 
  Since:  2012 
Syntax
Remarks
 The default is to include the shading surfaces.