A nonterminal definition is echoed if it is included in the grammar several times, each of which is identical to any other. Echoes were found in the Java Language Specification as a result of manual (not tool supported) creation of both the grammar and language documentation. They were merged in the grammar extractor – that is, during the phase of converting the original HTML document to the first version of the grammar [SCAM-J-2009-LammelZ11, p.348]. A similar error was observed earlier in the C\# standard [Too-Sharp2005] and later in other languages [Zoo2015].