Since the whole is unlike either of its parts, it is exocentric. In other words, since the whole is neither a noun (N) like "Hannibal" nor a verb phrase (VP) like "destroyed Rome" but rather a sentence (S), it is exocentric. With the advent of X-bar theory in Transformational Grammar in the 1970s, this traditional exocentric division was largely abandoned and replaced by an endocentric analysis, whereby the sentence is viewed as an inflection phrase (IP), which is essentially a projection of the verb (a fact that makes the sentence a big VP in a sense). Thus, with the advent of X-bar theory, the endocentric vs. exocentric distinction started to become less important in transformational theories of syntax, for without the concept of exocentricity, the notion of endocentricity was becoming vacuous.