Hypercorrection is always a function of rule generalization, though the converse does not hold. It is therefore a sociolinguistic term, not definable in purely linguistic terms. What is generalized is not necessarily the original rule of the grammar. It may be an added rule symmetrical to it. These symmetrical rules are not necessarily ‘Last rules’, for their output may undergo further non-hypercorrect rules. (Hypercorrection, sociolinguistics, phonological theory, historical phonology.)