This article describes an architectural framework of a multi-modal dialogue system. The framework is based on separation between the semantic and the syntactic parts of the dialogue. The semantics of the human-computer conversation is captured using a formal language. It describes the conversation by means of sequences of dialogue elements. The paper further elaborates how to derive the syntactic features of the conversation. A two-layer architecture has been proposed for the dialogue system. The upper layer, called sequencer, works with the description of the whole dialogue. The lower layer (driver dock) deals with individual dialogue elements.