A formal description of polish utterances with a vocative nominal phrase We describe an automatic processing approach to the problem of a vocative nominal phrase. The author of the formalism adopted here is Alain Colmerauer (1978). This formalism is known as «metamorphosis grammar». It was used to describe the syntax of the Polish language by Stanisław Szpakowicz (1983) and Marek Świdziński (1987) in Poland. The same metamorphosis grammars can be used for semantic models or models which take into account parameters of the speech acts. This is also our purpose here. The analysis of real utterances led us to reject the hypothesis that the vocative nominal phrase should be considered as a subject of the main verb. At the same time, it became obvious that it was necessary to take into account some parameters of the speech act (namely those refering to the speaker and the addressee) for the description of utterances with a vocative constituent. During the formalization process, we noticed that the «loose constituent» in the vocative case could not be generated only by a rewrite rule as it linked too closely the «loose constituent» with the sentence. For this reason, a procedure call had to be added to the raies. In our system, every linear expression uttered in a given speech situation is defined as an utterance, if 1) it contains a loose constituent (in the vocative case), 2) it contains an elementary well-formed sentence and 3) it refers to a speech situation. Without taking the speech situation into account, we have to bind the loose constituent to the sentence by syntactic rules. In our opinion, this stands in contradiction with the syntactic «independence» of the «loose constituent». The contradiction raises the problem of the syntactic nature of loose constituents in general. This is particularly important because not only a noun phrase in the vocative case but also some other phrases (among them modifiers such as temporal and local phrases, modal adverbs or particles) can be viewed as loose constituents of an utterance. The restrictions on the formation of utterances with the vocative noun phrase are not due to syntax but to the coreferential rules that anchor the linguistic expressions in given speech situations. Therefore, in our model, the speech situations are treated as procedure calls, because we think that such procedures allow the insertion of coreferential parameters during automatic processing of utterances.