Echo

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.

Reference

Mats Stijlaart and Vadim Zaytsev. 2017. Towards a taxonomy of grammar smells. In Proceedings of the 10th ACM SIGPLAN International Conference on Software Language Engineering (SLE 2017). ACM, New York, NY, USA, 43-54.