Related smells: Incomplete Abstraction, Unnecessary Abstraction, Unnecessary Abstraction, Compound Attribute, Multicolumn Attribute
When the right hand side of a nonterminal is formed from several symbols that happen to occur one after another, without forming a proper abstraction, this can hinder grammar's understanding. The terminology is borrowed from [McCord1985] which distinguished strong nonterminals (used during parsing and present in the resulting tree) from weak ones (used during parsing but flattened into single nodes in the tree).