Theory
In a context in which the Addressee wants to enter a field with a bull in it, a Speaker might exclaim:
Watch out, there’s a bull in the field!
In the prelinguistic Conceptual Component a communicative intention (issuing a warning) and the corresponding mental representations (of the event causing danger) are activated. Within the Grammatical Component, the operation of Formulation translates these conceptual representations into pragmatic and semantic representations at the Interpersonal and the Representational Levels respectively.
At the Interpersonal Level, the Speaker formulates a Move consisting of two Discourse Acts. The first (watch out) is a conventional, fixed expression used for urgently drawing the Addressee’s attention to an imminent danger – this expression is selected at the Interpersonal Level and immediately sent to the Phonological Level. Warnings are not a separate illocutionary category in English (unlike the Brazilian languages Desano, Kamayurá, Mayoruna, etc.), but the speaker solves this problem by formulating the second Discourse Act (there’s a bull in the field) as a Declarative Illocution combined with an Emphatic operator at the Interpersonal Level. The entity causing danger is furthermore characterized as a Focal Topic at this Level and the location (‘field’) is taken as being specific and identifiable (hence the definite article the).
At the Representational Level only the second Discourse Act is dealt with (since the first has been sent to the Phonological Level). Here, the Speaker chooses to designate the entity causing danger as part of a locative predication frame. The configurations of this Discourse Act at the Interpersonal and the Representational Levels are translated into a morphosyntactic structure at the Morphosyntactic Level through the operation of Morphosyntactic Encoding. This involves, for instance, the word order characteristic of existentials, the insertion of dummy there, as well as the insertion of the articles and of the verb be, etc.
Similarly, the structures at the Interpersonal, Representational, and Morphosyntactic Levels are translated and come together as an Utterance consisting of two Intonational Phrases (IPs) at the Phonological Level. In the second of these IPs, the selection of the declarative illocution combined with an emphatic operator is responsible for the overall intonation contour with a high fall on the Focal Topic bull. The Phonological Level of representation is the input to the operation of Articulation, which contains the phonetic rules necessary for an adequate utterance. Articulation takes place in the Output Component, outside the grammar proper.