sentences:  In the case where "Z" must be satisfied first, ANBN will fail to generate ', and thus "" is not generated by the grammar.Moreover, if either "Y" or "Z" (or both) specify any action to be taken upon reduction (as would be the case in many parsers), the order that these productions match determines the order in which those side-effects occur.Formalisms that vary over time (such as adaptive grammars) may rely on these side effects.