GRAMMATICAL INTRODUCTION
3.61 Fragmentary or elliptical clauses: a phrase or single word, such as could enter into the structure of a full clause if the rest of a full clause were uttered. Under this type come most cases of incomplete sentences in normal conversation, answers to questions, etc: ¿Qué le dijo?—Nada. "What did he say to him?—Nothing."; Buenos días. ¿Cómo está Ud.?—Muy bien, gracias. ¿Y Ud.? "Hello. How are you?—Very well, thanks. And you?"
3.62 Interjectional clauses, consisting of words which do not have the inflection or function of any of the parts of speech, and may be used as separate utterances or joined with other clauses: ¡Ah! "Ah!"; ¡Ay! "Ouch!"; ¡Hola! "Hello!"; ¡Oh! "Oh!"; etc.
