Related smells: Data Clumps, Reinvent the Wheel, Duplicate Block, Duplicated Formulas, Connector Envy
One step further, we may observe clones between two or more subexpressions found in different places in the grammar. The detection pattern is almost the same as with Foldable, but the solution must involve creating a new nonterminal and then folding it (extract in the terminology of [IFM-2009-LammelZ][SCAM-J-2009-LammelZ11]). Since creating a new nonterminal implies inventing a new name for it, and only suboptimal heuristics are available, the removal of this smell cannot be properly fully automated.