The use of pronouns often involves anaphora, where the meaning of the pronoun is dependent on another referential element. The referent of the pronoun is often the same as that of a preceding (or sometimes following) noun phrase, called the antecedent of the pronoun. The grammatical behavior of certain types of pronouns, and in particular their possible relationship with their antecedents, has been the focus of studies in binding, notably in the Chomskyan government and binding theory. In this binding context, reflexive and reciprocal pronouns in English (such as "himself" and "each other") are referred to as anaphors (in a specialized restricted sense) rather than as pronominal elements. Under binding theory, specific principles apply to different sets of pronouns.