Various models for categorizing grammatical units exist in the literature. Particularly nebulous, however, are terminologies for conceptualizing categories at the level of the clause. For example, the ...

The Oxford comma. “Ask” instead of “aks.” There, their, and they’re. The legitimacy of “ain’t” and “y’all.” These are familiar, if sometimes contentious, issues in the usage of the English language.

THE ancient notion of English grammar was one of certain categories of words, and certain rules for their proper use. This is still the idea implied in most of the dictionary definitions of the word.