An interface that supports addition of DB-level external applications to Revit, to subscribe to DB-level events and updaters. 
   Namespace:   Autodesk.Revit.DB  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 2015.0.0.0 (2015.0.0.0) 
Syntax
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Remarks
 DB-level applications are permitted to add DB-level events and updaters to the session. They cannot create or modify UI.