This method rolls back the work for the TDBXTransaction. Any active transactions that were begun after this transaction are freed and effectively rolled back as well. The variable Transaction instance is set to nil. 

Unlike the RollbackFreeAndNil procedure, this procedure does not throw an exception if Transaction is invalid or set to nil. This method is ideally used in a finally (or except) block. The try block uses either CommitFreeAndNil or RollbackFreeAndNil, and the Transaction has already been completed, freed, and set to nil. If an exception is not raised in the try block, a call to RollbackIncompleteFreeAndNil in the finally block does nothing, because the Transaction instance is no longer valid. If an exception is raised, a call to RollbackIncompleteFreeAndNil in the finally block rolls back, frees, and sets the Transaction instance to nil. 

TDBXTransaction 

CommitFreeAndNil 

RollbackFreeAndNil