Spillover

Spillover happens when some symbols that should have been a part of the nonterminal definition, are not included in its right hand side, and appended every time to its use. This creates a co-change relationship between the nonterminal and the context of its use. With Spillover, every time a definition of a nonterminal is changed in a particular way, all occurrences of the same nonterminal needs to be updated.

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.