+ /// Initialize iterator
+ virtual void First() {return;} // not yet virtual pure, waiting for trigger
+
+ /// DDL iterator
+ virtual Bool_t NextDDL() = 0;
+
+ /// Whether the iteration is finished or not
+ virtual Bool_t IsDone() const {return kTRUE;} // not yet virtual pure, waiting for trigger
+
+ /// add error message into error logger
+ virtual void AddErrorMessage() = 0;