True if the corresponding left/upper parts profile are mirrored with respect to the center line of the hosts to be divided. False if the profile of left/upper parts are defined directly by the profile family. 
   Namespace:   Autodesk.Revit.DB  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 2015.0.0.0 (2015.0.0.0) 
  Since:  2013