Dead

All top (unused) nonterminals identified as not being the starting symbol(s) of the grammar, represent unreachable fragments.

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.