Identifies if this ScheduleSheetInstance is a revision schedule in a titleblock family. 
   Namespace:   Autodesk.Revit.DB  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 2015.0.0.0 (2015.0.0.0) 
  Since:  2013 
Syntax
Remarks
 These schedule instances should not be modified in the project environment. To modify the revision schedule on a titleblock, edit the titleblock family.