Hallo Kaspar, thank you for your answer and thank you for Parslet! Could I easily add some extension code to get a message in this case, too? If yes, where is/might be the "start point"? Kind regards, Axel Kaspar Schiess wrote in post #1114730: >> Or, in which cases results are lost/merged silently? > > Only in one case: When merging a subtree containing .as(...) with > another subtree that doesn't. The solution is in most cases to add more > annotations (.as). -- Posted via http://www.ruby-forum.com/.