The newly added external data instance id. 
   Namespace:   Autodesk.Revit.DB.Events  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 23.0.0.0 (23.1.0.0) 
  Since:  2023 
  Namespace:   Autodesk.Revit.DB.Events  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 23.0.0.0 (23.1.0.0) 
  Since:  2023