The category ambivalence of polylexical units

On tries to answer the following questions: how does the dictionary determine the syntactic category of polylexical units? What place does he reserve for the ambivalence of this type of units? What place does he reserve for ambivalence of this unity? What relationship is established between micro- and macro-syntax in the description of polylexical units? Particular interest will be reserved for the parts of speech the definition of the lexical unit and the primary functions.